以下是我做过练习中没弄明白的错题,我给出了正确答案和我自己选的答案,麻烦大家帮我指出我错在哪?为什么错?

以下是我做过练习中没弄明白的错题,我给出了正确答案和我自己选的答案,麻烦大家帮我指出我错在哪?为什么错?
分数50分,给出解析,一共11题,解析最全的回答做为最佳答案,毕竟是为了自己能弄懂这些题,要是解析能帮到我的话,
1.He will pass two milestones_____,that is,he will receive his master's degree and find a challenging job.
A.long ago B.not long ago C.before long D.long before
2.He's not got another job yet and it's not_____he will for some time.
A.likely B.easily C.nearly D.lonely
正确答案A,我选择B
3.A left-luggage office is a place where bags_____be left for a short time,especially at a railway station.
A.should B.can C.must D.will
正确答案B,我选择D
4.The managers discussed the plan that they would like to see_____the next year.
A.carried out B.carrying out C.carry out D.to carry out
正确答案A,四个选项分别解析一下
5.--What do you think made Mary so upset?
--_____her new bike.
A.As she lost B.Lost C.Losing D.Because of losing
正确答案C,我选择D
6.The lady said she would buy a gift for her daughter with the_____.
A.20 dollars remained B.20 dollars to remain
C.remained 20 dollars D.remaining 20 dollars
正确答案D,我选择B
7.There are five pairs_____,but I'm at a loss which to choose.
A.to be chosen B.to choose from C.to choose D.for choosing
正确答案B,我选择A
8._____in 1636,Harvard is one of the most famous universities in the United States.
A.Being founded B.It was founded C.Founded D.Founding
正确答案C,我选择B
9.The picture_____on the wall is painted by my nephew.
A.having hung B.hanging C.hangs D.being hung
正确答案B,我选择D,难道这不是用被动语态（画被挂在墙上）吗?
10.Sandy could do nothing but_____to his teacher that he was wrong.
A.admit B.admitted C.admitting D.to admit
正确答案A,我选择B,
11.I would have come earlier,but I_____that you were waiting for me.
A.didn't know B.hadn't know C.would have known D.haven't known
正确答案A,我选择B
提问截止至3月3号!