甲，乙两人练习跑步，若乙先跑10米，则甲跑5秒就可以追上乙；若乙先跑2秒，则甲跑4秒就可追上乙．若设甲的速度为x米/秒，乙的速度为y米/秒，则下列方程组中正确的是（　　）

“一骑红尘妃子笑，无人知是荔枝来”。荔枝曾经是一种很奢侈的水果，现在却进入寻常百姓家。这说明(　　)

— That mountain in Guilin ________ an elephant.

— So it does. It's amazing!

根据短文内容，判断下列各句正误。

    Here's the weather report for today. It's going to be dry and windy for most of the day. Because of the wind, it's going to be cooler than usual. And the wind is going to be stronger in the evening.

    Now the report for the weekend. Our Saturday morning is going to be cloudy with little rain. And it's going to be cooler than today. In the afternoon the clouds will lift and the sun will come out. We shall have a warm evening.

    On Sunday the weather is going to change again. It's going to be fine and hot. But at noon a wind will come and it's going to be stronger in the afternoon. It's going to be a little cooler in the afternoon.