个别问题我有一些具体的疑问.1.（）you swim when you ()five years old?A.Can,a

个别问题我有一些具体的疑问.
1.（）you swim when you ()five years old?
A.Can,are B.Can,were C.Could,were
2.Mr Green () all his time teaching the students.
A.takes B.spends C.uses
3.If the telephone(),can you answer it?
A.rings B.is ring C.will ring
在这里If the telephone(),是不是一个从句啊
如果主句没有用将来时态,从句可以用吗?
4.***(人名)'s parents bought a new house () the money that *** gave them.
A.in B.with C.use
第1题，如果选C,前面已经表明是过去式了后面为什么还要用were呢？