按要求改变下列句子。
1.Their dictionaries are on the desk. (对画线部分提问)
_____ _____ their dictionaries?
2.There is a library behind the science lab. (变成一般疑问句,并作肯定回答)
--- ______ _____ a library behind the science lab?
--- Yes, _____ _____.
3.My book is behind the desk. (变成一般疑问句,并作否定回答)
-- _____ ______ book behind the desk?
-- No, it _____.
4.They are not pencil- boxes. (改为单数句)
It ____ _____ ____ pencil-box.
5.You and I are in the gym now. (用复数第一人称代替画线部分)
______ are in the park now.