产前检查应从什么时间开始（）
A.从确诊早孕开始
B.从妊娠6周开始
C.从妊娠12周开始
D.从妊娠20周开始
E.从妊娠24周开始
参考答案：A
1.5摩尔气体在标准状态下的体积是（）。
A.22.4L
B.33.6L
C.22.4m3
D.33.6m3
— Do you know when the technology for hybrid rice to the United States?
— Yes. In 1980. [ ]
A. introduced
B. introduces
C. is introducing
D. was introduced
