选择适当的情态动词填空。
The box ________ (must, need) weigh more than twenty kilos. I can’t carry it.
You _______ (can, should) keep in line to check out.
—Can I take this book out of the library?—No, you _________ (may not, mustn’t).
__________ (may, can) you see some birds in the tree？
You _______ (can’t, might not) do it like that. It’s forbidden.