tow hours在什么情况下用for two hours

1、Two hours_is__enough for us to arrive there on time(C)时间做主语时谓语用单数
A.are B.has C.is D.was
2、I met one of the boys who _was__going to come to China the next month.(C)首先,宾语从句中的时态,当主句是一般过去时时,从句要用相应的过去时态,在这里,met提示主句是一般过去时,所以从句中的助动词也要用过去式,若用would,则后面用go而不是going,所以用was
A,were B.is C.was D.would
3、Either of the plans_is__equally dangerous.(B)either of 修饰主语,谓语用单数
A.are B.is C.has D.have
4、_Both__English__and_French are taught in this school.A)所给的四个短语中,either or和not only……but also要考虑就近原则,与谓语的复数形式不符,both of后用名词复数,与题意不符,而both……and连接并列的两个名词,谓语用复数
A.Both,and B.Either,or C.Both of ,and D.Not only,but also
5.There __was__no hospital in our town in the past.（B)首先,根据时间状语in the past考虑用一般过去时,又因为no修饰后面的名词,所以谓语用单数
A.is B.was C.are D,were
6.He is the only one of the students who __is_elected(D)首先,electde是elect的过去分词,意为当选的,应使用被动语态,且one of修饰先行词students,所以定语从句的主语是单数,谓语用单数.
A.are B have C.has D.is
7.What we need _is__good textbooks.(A)what连接主语从句,谓语用单数.
A.is B.are C have D.has
8.This is one of the best novels that__have___appeared this year.(B)宾语从句的主语that指 best novels所以是复数,从句的谓语用复数.又因为根据句意应是“今年出版的”,不适用被动语态,所以填have.（zhidao.baidu.com/question/227390724.html）
A.have been B.has C ,had been D.have
9.It_is__I who_am_leaving for London.(C)强调句It is…… that,判断thatwho后面的谓语时直接将It is……that省略再判断.
A.is...is B.am.is C.is.am D.am.am
10.That they were wrong in these matters_is___now clear to us all(A)that引导的主语从句,主句谓语用单数.
A.is B,was C .are D.were

another two hours（已有两小时,共四小时）,two more hours（再两小时,不标明之前的时间）；other two hours其他的（剩下的)两小时,在一定范围中；two other hours（强调数目,前面没有提到具体范围） ；two hours more又（延长了、呆了等）两小时；

will last
last:持续

for
表示一段时间用介词fo