照例子写出下列动词的变化形式.例：look-looks-looked-looking

1.work works worked working
2.go goes went going
3.ask asks asked asking
4.make makes made making
5.do does did doing
6.have has had having
7.stop stops stopped stopping
8.eat eats ate eating
9.drink drinks drank drinking
10.sing sings sang singing
11.fly flies flew flying
12.swim swims swam swimming