单项选择题
When he suddenly（） up the subject of genetic engineering, there was an embarrassed silence.
A.took B.brought C.showed D.came
单项选择题 The problem（）when the students refused to do their homework.
单项选择题 Speaker A: Want to come over Thursday for supper? Speaker B:（）
单项选择题 Mickey: You look a little pale. Are you OK? Nancy:（）I feel terrible.
