煤一般发育于（）中。
A.岩浆岩
B.沉积岩
C.变质岩
D.火成岩
参考答案：B
You should try to get a good night sleep____ much work you have to do.
A．however
B．whatever
C．no matter
D．although
计算机的特点包括哪些？
