C is changed to have lost because had they = If have then is used to represent the hypothesis contrary to the past facts, then the main clause should use have lost. (Be sure to master the subjunctive mood of unreal conditional sentences guided by if)
If it is done by hand, the millions (complex) calculations involved will lose all practical value.
2. Folk songs are characterized by: (a) informal wording, (b) relying heavily on actions and dialogues, (c) thematic content and (d) emphasizing repetition.
C. change it to intensity, because intensity is an adjective and should be in the form of a noun. Theme of consciousness is an adjective that modifies nouns. Secondly, it can be seen that four by phrases form a parallelism sentence, and the others are all noun forms, such as: diction, action, repetition.
Translation: Folk songs are characterized by the use of informal language, mainly relying on the narrative style of action and dialogue, intense topics and repeated emphasis.
3. The manufacturing cost of cars is extremely expensive until the assembly line technology reduces the production cost.
A change it to a car. Note that they were made for later use.
Automobile manufacturing was very expensive before assembly line was assembled.
4. Sleep is controlled by (a) brain (b) and associated with (c) unique breathing rhythm (d).
C is changed to be associated with the phrase.
Sleep is controlled by the brain and related to the unique breathing rhythm.
After graduating from high school, the village education committee appointed him to teach in primary school.
A. change it to When he had finished, because when a participle is used as an adverbial, its logical subject should be consistent with the subject of the sentence. The subject of the sentence here is the village education Committee, but the logical subject of the present participle has finished reading high school. So it is correct to change it into an adverbial clause.
After he graduated from high school, the village education Committee arranged a teaching position for him in the primary school.
After graduating from high school, he went to work in Beijing.
No matter how hard she tries, she can hardly avoid making grammatical mistakes in her composition.
D. It is changed to how because how means that no matter how much attention is paid to all conjunctions with -ever, they can guide both adverbial clauses and nominal clauses, and add "no matter" when translating into Chinese.
No matter how hard she works, she can hardly avoid grammatical mistakes in her composition.
I can't imagine how hard his past life was.
I can't imagine how hard his past life was.
7. Have you ever read in Columbia spectator that Giff broke his leg while playing football?
D. it is changed to while he are playing because the subject of the adverbial clause is the same as that of the main clause, and it can only be omitted if the clause contains be. Here the subject of the main clause is Jiff's leg, and the subject of the clause He cannot be omitted.
Did you read in the Columbia Observer that Jeff broke his leg while playing football?
8. That night, although he was very tired, the federal official went out for help again.
B. It is changed to though he was because through can be inverted when guiding adverbial clauses, and the predication should be mentioned at the beginning of the sentence.
Although the EU official was very tired that night, he went out for help again.
Supplement: the adverbial clause guided by though can be inverted or not.
But when as is "although, although", the leading adverbial clause must be inverted. This kind of inversion is special, so we should advance the predicative or adverb.
Child as he is, he knows a lot. (note that there is no article before child)
Young as he is, he knows a lot.
When there are no predicates and adverbs, the prototype of verbs can be advanced.
Despite her best efforts, carolina couldn't open the door.
When scientists first put forward the possibility that one person can talk to another person directly from a distance, few people took it seriously.
A is changed to imaginative, which means "imaginative" and can modify people.
When imaginative scientists suggest that one person can talk directly with another person who is far away, few people take it seriously.
Comparison: imaginable is often used with superlative adjectives or all, every, the only, after the modified noun.
This is the only conceivable solution. This is the only conceivable solution.
10. The economic difficulties of this country will not disappear unless cheap fertilizers can be widely distributed.
A changed to economy means "economy, economy, economy"
The country's economic difficulties will not be alleviated unless cheap fertilizers are widely distributed.
Economical; economic
A thrifty person.
I hope I can help you! Let's work hard and study together!