还请高手帮我看看 下面句子是什么结构的句子.感激不尽

还请高手帮我看看 下面句子是什么结构的句子.感激不尽
I.Decide which type of sentence each of the following belongs to and then choose the corresponding letter.
1.It is a pleasure to read good books.（ ）
A.periodic sentence B.compound sentence
C.balanced sentence D.loose sentence
2.She missed the step and sprained her ankle.
A.periodic sentence B.compound sentence
C.simple sentence D.loose sentence
3.Mary had to give up watching TV,for she must take the exams.
A.complex sentence B.compound sentence
C.simple sentence D.compound-complex sentence
4.She decided to study English though she was interested in music.
A.periodic sentence B.compound sentence
C.balanced sentence D.loose sentence
5.There were the translators in their booths,and the girl secretaries at the doors,and the reporters grumbling and scribbling in their seats.
A.periodic sentence B.compound sentence
C.balanced sentence D.loose sentence