一．单项选择（共30题，每题1分， 共30分） 1. it's very dangerous to be ____ to the sars virus without any protection. a disclosed b uncover c affected d exposed 2. he always brings me a pretty gift ____ he comes to visit me. a by the time b sometimes c every time d at times 3. ---- do you _____ any difficulty ______ the subject ? ------ yes. it’s too hard for me. a.take; to understand b. have; in understanding c.take; understanding d. have; to understand 4. it is human activities on the earth that are to _______ global warming. a. be blamed for b. to blame for c. take charge of d. be responsible with 5. not everybody attending the meeting agr
