题型:问答题 简答题 — Simon, I wonder ________. — Last Saturday.A.when did the foreign visitors arriveB.when the foreign visitors arrivedC.when the foreign visitors will arriveD.when will the foreign visitors arrive 查看答案
题型:问答题 简答题 当温度太高或太低,不能用任何一种油液或脂或其他液体作为润滑剂时,或不允许有油脂污染,或在有尘土、酸、碱性腐蚀的环境中,或在高真空、强辐照条件下运行是,可选用()润滑剂。A.固体B.液体C.气体D.固液混合 查看答案