Homework: Use the following expressions instead of I don't know in your sentences. numbers 6-8 on page 52 :)
I don't remember...
I can't remember...
I've forgotten...
I'm not sure ...
I have no idea...

How long have the Wilsons been married?
1.I don't remember how they long =long they  have been married.
2.I can't remember how they long =long they have been married.
3.I've forgotten how they long =long they have been married.
4.I'm not sure how they long =long they have been married.
5.I have no idea how they long = long they have been married.

How long has Alice been working here?
1.I don't remember how she long have =long she has been working.
2.I can't remember how she long have =long she has been working.
3.I've forgotten how she long have =long she has been working.
4.I'm not sure how she long have =long she has been working.
5.I have no idea how she long have = long she has been working.

Who should I vote for?
1.I don't remember who you should vote for.
2.I can't remember who you should vote for.
3.I've forgotten who you should vote for.
4.I'm not sure who you should vote for.
5.I have no idea who you should vote for.

When is Santa Claus going to come?
1.I don't remember when Santa Claus is going to come.
2.I can't remember when Santa Claus is going to come.
3.I've forgotten when Santa Claus is going to come.
4.I'm not sure when Santa Claus is going to come.
5,I have no idea when Santa Claus is going to come.

good job! Lucy ^^* but the only thing I corrected is the question with How long + subject ok.. :)