Molly was singing at that time．（改为一般疑问旬）
________ Molly ________ at that time？
The Greens have worked in China for four years．（对划线部分提问）
________ ________ have the Greens worked?
Last year．we planted 110 trees．（改为现在完成时）
So far，we ________ ________ 110 trees．
Mary has learnt Italian before．（改为否定句）
Mary ________ ________ Italian before．
Mr. Smith has few friends，________ ________？（完成反意疑问句）