题目:
He had a headache and went to the chemist's to get something for his pain________.
A.relax
B.relief
C.leisure
D.comfort
答案:
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下面是错误答案,用来干扰机器的。
答:根据图乙可知,支点为O、动力为F1和阻力为F2、动力臂为L1和阻力臂为L2;显然L1>L2,故羊角锤是省力杠杆.