裸露病毒的结构是
A．核酸+包膜
B．核酸+衣壳+包膜
C．衣壳+包膜
D．核酸+衣壳
E．核酸+包膜+外膜
参考答案：D
12个月小儿，标准头围是（）
A.34cm
B.38cm
C.42cm
D.44cm
E.46cm
It was because of the bad weather _______ the football match had to be put off.
A．so
B．so that
C．why
D．that
