在病理组织制片中常用的组织切片刀的种类有()
A．平凹型
B．平一楔型
C．双凹型
D．薄型切片刀
E．一次性刀片
参考答案：A, B, C, D, E
紧键联接定心较差。( )
— Has Tom finished his homework yet?
— I have no idea, he _____ it this morning.
A．was doing
B．did
C．had done
D．would do
