Malaysia Airlines Flight MH370 was expected to land in Beijing the morning of 2014,March 8.

ent Obama held talks with ChinesePresident Hu Jintao in Beijing, ________ economic recovery, climate change andstopping the spread of nuclear weapons

Teachers required that all the students ___ their homework all alone.

In my opinion, ______ seems easy at first often turns out to be difficult in the end.

o cause us some health problems, in fact, farmore serious ________ than mobile phones do.