选词填空。 1. We _____________ (has, have) a new teacher. 2. Let _____________ ( us, is) clean the window. 3. How many _____________ (pen, pens) do you have? 4. _____________ (I, My) schoolbag is heavy. 5. _____________ (I, He) likes music. 6. He's good _____________ (for, at) math.