英语几道名词性从句的题!谁会?（详解）

英语几道名词性从句的题!谁会?（详解）
1)No one knows exactly _d_ this important discovery was made.
A that B that how and when C how or why D how or when
2)I haven't found my pen yet.In fact,I am not sure _d_I could have done with it.
A whether B where C how D what
3)He often thinks of _b_ he can do more for his country.
A what B how C that D which
4)Mr.Green goes to his office on foot every day_c__it rains heavily.
A when B except C except when D but
5)They have decided to go on a trip to the Great wall,but _a__they are to do so hasn't been made clear yet.
Awhen B what C where D whether
6)Don't tell the news to __a_.
A whoever you meet B whoever is it C whichever he wants D whoever wants
7)The true value of life is not in __b_.
A which we get,and what give us B what we get,but what we give
C which we get,and what we give D how we get,but that we give