按要求改写下列句子。 1.She has been working for 20 hours.(改为一般疑问句,并作否定回答) she working for 20 hours?No, . 2.I've been skating since l was six years old .(对画线部分提问) you been skating? 3.Tom ran for one hour.(用现在完成进行时改写) Tom for one hour. 4. We have been learning English for three years.(改为同义句) We have been learning English . 5. I started playing tennis when I was seven years old. (改为同义句) I started playing tennis seven.