-Have you got the airplane tickets? -No, because it's May Day ,all the tickets to Beijing______out.
He _______ you an e-mail as soon as he ________ a plan.
Aron ______ water five days later.
This is______ difficult problem that few students can work it out.
Some people plan to ______ a volunteer project to help the disabled children.
---My mother is ill in hospital. ---______