在10以内的自然数中，互质的两个合数有______组．
解；在10以内的自然数中，互质的两个合数：4和9、8和9，一共有两组．
故答案为：两．
__ __ many Chinese women have received higher education, there are still obstacles that prevent them from enjoying the same opportunities for education and employment as men．
A．Whether
B．Because
C．When
D．Although
碎煤机强烈振动，电流突然上升并有严重声响的原因是（）。
A.机腔堵煤
B.碎煤机轴承损坏
C.大块煤进入碎煤机
D.大块煤石或铁块进入碎煤机
