非谓语动词练习 （ ）
1 The old man,______abroad for twenty years,is on the way back to his motherland.
A to work B to have worked C working D having worked
2 Having been ill in bed for nearly a month,he had a hard time____exam.
A padd B to pass C passed D passing
3 Generallly speaking,_____according to the directions,the drug has no side effect.
A when taking B when taken C when to take D when to be taken
能否给一些指点