第5题: [单项选择]主机在长时间停车后的起动过程中,主、辅起动阀开启与关闭的情况为()。 A. 辅阀开,主阀关-辅阀关,主阀开-主阀关 B. 辅阀开,主阀关-辅阀开,主阀开-主阀关,辅阀关 C. 辅阀关,主阀开-辅阀开,主阀开-主阀关,辅阀关 D. 辅阀关,主阀开-辅阀开,主阀关-辅阀关 参考答案:B
A. we plant more trees B. we be taught environmental science, as well as the science of plants C. environmental education be directed toward everyone D. we return to nature 参考答案:C 答案解析:文章第三段提到“For the sake of ourselves and those who will come after us,we must now set about repairing t
第34题: [单项选择]板链提升机用的板链由()等组成。 A. 内、外链板、套筒、滚筒及销轴 B. 链环与钩环 C. 传动链条、接紧链条 参考答案:A