面角恒等定律
参考答案：
同种物质的晶体，其对应晶面间的夹角守恒。
_______will Mr. Black be able to regain control of the company.
A．Only by working hard
B．Only he works hard
C．With hard work
D．Only if work hard
"Would you like to drink milk? Thank you, but just _________." [ ]
A. a few
B. few
C. a little
