采用双金属活塞主要优点是（）。
A.限制活塞裙部膨胀量
B.增加刚度
C.节省材料
参考答案：A
Her parents want her to _____in a government office, saying that a _____ job means ______income, but she thinks the other way around. [ ]
A. employ; secure; secure
B. be employed; certain; certain
C. employ herself; sure; sure
D. be employed; secure; secure
团队精神意味着[ ]
①善于合作
②集体成员能够主动与他人合作
③同伴互帮互助、取长补短
④为了实现共同的目标而共同尽心尽力
A．①②③
B．①③④
C．②③④
D．①②③④
