High-tech machines have made life easier for millions around the world．However, some people still prefer low-tech ways of doing things．Here’s an example of why this is happening．You can micr
地质学家常利用地震波来寻找海底油气矿藏，下列四幅地震波示意图中表示海底储有石油的（ ） A．① B．②① C．③①
—How do you say 3，365 in English? —It’s________． A．three thousand，three hundred and sixty five B．three thousand and three hundred sixty five C．
She can’t help_________ the house because she’s busy making a cake. A. to clean B. cleaning C. cleaned D. being deaned
读图回答问题。 甲、乙两城市之间的铁路线，在①、②两处出现明显的弯曲，其目的 （ ） A．①处是为了
有一滑轮组的结构不清楚．当用向下的动力F匀速将绳的自由端拉下 5m时，重为2000N物体匀速上升lm。求： (1)当动滑轮的重量和摩擦都不计时．动力F是多
—Where did you get this book? —I picked it up from a secondhand bookshop if you ________ know. A．must B．will C．can D．shall
下列各组混合物中，能用分液漏斗进行分离的是（ ）。 A．酒精和水 B．碘和四氯化碳 C．水和四氯化碳 D．汽油和植物油
．
得：x＜3