句型转换。 1.Please draw a picture now. (改为否定句) Please ______ a picture now. 2.These are cameras. (改为单数句) ____________a ______. 3.Feed the cat, please. (改为否定句) ____________ the ______, please. 4.This is a fountain. (改成复数句) _____________________. 5.The books are on the desk. (根据划线提问) _____________the books?