烟叶醇化需要的时间和（)因素有关。A.烟叶化学成分B.环境温度C.烟叶水分D.以上都不对

微核试验主要反映的遗传终点为

A、DNA完整性改变

B、DNA重排或交换

C、DNA碱基序列改变

D、染色体完整性改变

E、染色体分离改变

请帮忙给出正确答案和分析，谢谢！

According to the report, which statement is NOT mentioned？

A．The benchmarks could be as high as 18,500 yuan per month in Hong Kong.

B．The Chinese Academy of Social Science also released its findings in 2006.

C．The benchmarks at the upper end are 8,900 yuan in Macao and 5,350 yuan in Shanghai.

D．At the lower end are 1,300 yuan in Nanning and 1,100 yuan in Yinchuan and Xi"ning.

请帮忙给出正确答案和分析，谢谢！

On which holiday pumpkins are a very important part of celebration？

A．Halloween.

B．Thanksgiving.

C．Christmas.

D．New Year.

请帮忙给出正确答案和分析，谢谢！

David Hu and his colleagues analyzed the frozen ant rafts with______.

A．a small robot

B．a video camera

C．advanced materials

D．a CT scanner

请帮忙给出正确答案和分析，谢谢！

A PIN is necessary for______.

A．the activation of your credit card

B．online shopping with a credit card

C．your using credit card in shops

D．withdrawing cash through a credit card

请帮忙给出正确答案和分析，谢谢！