When once you have had the disease, you are______ to it for the rest of your life.A．immune

The bus had gone when I ____ at the bus stop.A、have arrivedB、arrivedC、had arrivedD、am a

When is the toy dog a good choice？A．When you have small children.B．When you live in the co

Once you _____ the knack of it, you will have no further difficulty.A.shall haveB.had h

We our breakfast when an old man came to the door.A.just have hadB.have just hadC.just had

Don’t stimulate the incision when you have a swimming.

Once you _____ the knack of it you will have no further difficulty.A.shall haveB.had h