In the past few decades, scientists have made a great ________ in the treatment of cancer.

下列各句中，没有语病的一句是（ ）

nd Chris, volunteers from Australia, are said _____ our school as they have finished their teaching mission.

The Chinese scientists claimed _______ a cure for the disease．

(2013·高考福建卷)Mrs.Smith finds it hard to clear up the mess，as her children are always ________ whenever she tries to