岩心长
参考答案：取出地面岩心的实际长度。
( )是指直接作用于感觉器官的客观事物的整体在人脑中的反映。
A．感觉B．知觉C．记忆D．思维
The number of books in the bookshop is about 10,000 and a number of them _______ about science.[ ]
A. is
B. was
C. are
D. were
