问题
选择题
已知实数a、b、c满足：a＜0，a-b+c＞0，则一定有 [ ]
A、b2-4ac＞0
B、b2-4ac≥0
C、b2-4ac≤0
D、b2-4ac＜0
答案
答案：A
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已知实数a、b、c满足：a＜0，a-b+c＞0，则一定有 [ ]
A、b2-4ac＞0
B、b2-4ac≥0
C、b2-4ac≤0
D、b2-4ac＜0
答案：A
| 从方框内选择正确的选项，完成短文，并把字母序号填写在短文中的横线上。其中有两个选项 是多余的。 | |
water and 1._________ the students "how heavy do you think this glass of water is?" The students' answers were from 20g 2._________ 500g. The teacher said, "It does not depend on the weight (重量) of the glass of water.It depends on how 3.________ I hold it. If I hold it for a minute, it is OK. If I hold it for an hour, I will have an ache in 4.________ arms. If I hold it for a day, I will 5._________ call an ambulance (救护车). The weight of the glass of water 6.________ change, but the longer I hold it, it becomes. Stress in our 7.________ is just like this. If we carry our stress all the time, we will not be 8._________ to continue our study, since stress becomes stronger. What you have to do is to put the glass down and rest for a while before you 9.________ again. We have to 10._______ from time to time in order to work on again. In this way, out stress will get less and less." |