英语选择________is often the case,too much discussion produces n

英语选择
________is often the case,too much discussion produces no agreement.
A)It C)As
B)Which D)That
I have promised to the manager that I______ the report by the end of this week.
A) will have finished C) will be finishing
B) should be finishing D) am going to finish
Many developing countries find it difficult to introduce birth control,________their population
Is already very large.
A)so C)since
B)because D)although
说下原因