1J等于（）N•m。
A、1
B、9.81
C、1000
D、9810
参考答案：A
He told me that he had two girl-friends, and neither of _______ knew anything about the other.
A．them
B．whom
C．which
D．who
哺乳期是指产后：
A．6周
B．4个月
C．6个月
D．10个月
E．1年
