ars, it was viewed as a serious problem,________ that has never been really solved.

–What’s troubling him ______did Jim look quiet withhis friends around–He’s considering a new project in his company

It didn’t take long for them to ______ the cheat，who pretended to be an expert in this field.[ ]

The plant is deadI ______it more water

The driver was not ____ for the traffic accident, was he’?— _____.It was the pedestrian’s fault. [ ]