三角贸易是人类历史上悲惨耻辱的一页,它持续了三百多年。下边“三角贸易”路线示意图中的“归程”路线是指( )
——Have you watched the TV report about MERS? ——Yes, it's _________ new dangerous disease(疾病).
以下几个实验现象,能说明声音产生原因的是( )
—When do you get up every day?—I usually get up_____ six o'clock.