What is it ________ made her upset— It is the missing bike.

_____reduce pollution, the government has made a policy to restrict the use of plastic bags in some areas.[ ]

She has been working hard day and night, which of course, _______ her pale face.

She didn’t come to the party last Sunday. _________,she must have made the party more exciting.

I have been living in the United States for twenty years, but seldom _____ so lonely as now. [ ]