Gary, please do me a favor--- _____ my laptop for me.
Someone called me up in the middle of the night, but he hung up __ I could answer the phone.
— Why do you look sad?— There are so many problems _____.
There’s no doubt ________ international cooperation is the key to ______ with cybercrime.(网络犯罪)
As is known to all, the financial crisis firstly broke out in the United States _______ the group of developed countries.
-------Let’s go to the concert this weekend.--------________.I’ve heard my favourite pianist Lang Lang is coming.