It’s difficult to live in a foreign country, ______ if you can’t understand the language there.

Sheuntil his mother got back home.That’s why she was so tired.

Let’s start the trip ______ half past eight ______ the morning of February 21.[ ]

Things made by hand are usually more expensive than _ produced in factories.

The work is too difficult for Mr Zhu to finish in a week. He needs ___________ days.