The traffic slowed down because of the heavy snow in Yushu County, presenting a new ____ to the recovery from the earthquake.
Sorry, LiMing, I’m afraid I have to ______. Someone is calling me.
Jack went back home after a heated discussion, _______.
Mary can speak Chinese fluently, _____ impressed me most.
Generally speaking, according to the directions, _____ the drug has no side effect.
According to the rules of the library, a book can _____ for three weeks, and a DVD for one week.