—How much of the foreign expert's speech have you understood?

—Next to nothing.I wish I ________ harder at English.[ ]    

A. had worked  

B. worked

C. would work  

D. were working

定量研究的准备阶段的工作包括（ ）。

A．制订研究方案

B．进行研究假设

C．归纳事实

D．提出问题

E．收集资料