II. Fill in the blanks with correct prepositions or conjunctions.1. Are the doctors able to track ________ the cause of the infection?
举一反三
- Time is running______ . (Fill in the blanks with the correct prepositions or adverbs.)
- We must not act ______ impulse. (Fill in the blanks with the correct prepositions or adverbs.)
- Part II. Fill in the blanks with appropriate prepositions and adverbs. (15%)Can I buy you lunch in return ______ your help?
- Our machines are out of date. We need to replace them______ new ones. (Fill in the blanks with the correct prepositions or adverbs.)
- Fill in the blanks with suitable prepositions or adverbs.