题目

A group of graduates got together to visit their old university professor.The conversation soon turned into__1__about stress in work and life.Offering his__2__coffee，the professor went to the kitchen and__3__with a large pot of coffee and a__4__of cups—porcelain，plastic glass，crystal，some plain­looking，some expensive，some exquisite (精致的)，telling them to __5__themselves to the coffee. When all the students had a cup of coffee in hand，the professor said，“If you have__6__，all the nice­looking expensive cups have been__7__，leaving behind the plain and__8__ones起重机吊起重物在空中静止不动时，钢索的拉力是4×106N，则重物所受的重力大小（ ）A．大于4×106NB．等于4×106NC．小于4×106ND．条件不足，不能确定