There is an increasing concern _____________ about Ebola infection. Every country has taken necessary measures to prevent it.
The reason why I was late was that I was ______ by the traffic jam.
None of us expected that the chairman ______ at the party. We thought he was still in hospital.
The teacher simplified the reading materials, ______ it easy for the students to read.
The British team, ______ several attempts to climb Yulong Xueshan, decided to have another try this summer.
—You didn’t wait for Mr. Smith last night, did you? —No, but we ______. He didn’t return home at all.