21.He is the only person who can ____ in this case, because the other witnesses were killed mysteriously.

　　A) testify

　　B) charge

　　C) accuse

　　D) rectify

　　22.Professor Hawking is ____ as one of the world's greatest living physicists.

　　A) dignified

　　B) clarified

　　C) acknowledged

　　D) illustrated

　　23.The financial problem of this company is further ____ by the rise in interest rates.

　　A) increased

　　B) strengthened

　　C) reinforced

　　D) aggravated

　　24.We shall probably never be able to ____ the exact nature of these sub-atomic particles.

　　A) assert

　　B) impart

　　C) ascertain

　　D) notify

　　25.All the people in the stadium cheered up when they saw hundreds of colourful balloons ____ slowly into the sky.

　　A)ascending

　　B)elevating

　　C)escalating

　　D)lingering

　　26.Many years had ____ before they returned to their original urban areas.

　　A) floated

　　B) elapsed

　　C) skipped

　　D) proceeded

　　27.What you say now is not ____ with what you said last week.

　　A) consistent

　　B) persistent

　　C) permanent

　　D) insistent

　　28.Military orders are ____ and cannot be disobeyed.

　　A) defective

　　B) conservative

　　C) alternative

　　D) imperative

　　29.Some educators try to put students of similar abilities into the same class because they believe this kind of ____ grouping is advisable.

　　A) homogeneous

　　B) instantaneous

　　C) spontaneous

　　D) anonymous

　　30.Even sensible men do ____ things sometimes.

　　A) abrupt

　　B) absurd

　　C) acute

　　D) apt