秤砣 chânɡ tuï
参考答案：
相当于砝码。若将一刻度准确的杆秤的秤砣挖去一小块，则称物体时读数比物体的实际质量大。
He began to __________ because every means _______ tried already.
A．lose heart; has been
B．lose heart; had been
C．lose his heart; was
D．lose his heart; had
在地面当机翼防冰接通时会出现什么情况（）
A.防冰活门一直打开
B.防冰活门打开30秒，然后关掉
C.防冰活门不打开
