We are not sure if it        tomorrow. If it        , our sports meeting will be put off.

In summer, food goes bad easily         it is put in the refrigerator.

—I hear Jack Chan will come to Laiwu next week.—Really?        he comes, my younger sister will be very happy.

        it's difficult to make her dream come true,she never gives up.

You should go over your test paper       you hand it in.

We won’t start the meeting        our teacher arrives.

下列生活实例与所运用的物理知识的说法,错误的是(    )

落满树叶的道路上,当一辆高速行驶的汽车经过时,树叶会(    )

下列四个事例中不属于利用大气压的是(    )

用托里拆利实验测定大气压的数值(玻璃管内水银面上方是真空).下列过程会导致测量数值发生变化的是(    )