A．gradually reduced B．difficult to predict C．still very powerful D．sometimes quite weak
单项选择题If you try to pass （） the problems, it would be impossible for you to make any progress in this field.
A．off B．over C．by D．across
单项选择题Once he set his mind to（）something, he would not give up easily.
A．do B．doing C．be doing D．having done
