一束光线从空气斜射入玻璃中会发生折射,当入射角减小时,折射角( )
A:逐渐减小,但总小于入射角
B:逐渐增大
C:逐渐减小,但总大于入射角
D:保持不变
已知函数f(x)=ax2+(b﹣3)x+3,x∈2a﹣3,4﹣a是偶函数,则a+b= ____
猪笼草是一种食虫植物,为了验证猪笼草分泌液中有蛋白酶。某学生设计了两组实验,如图所示。在35℃水浴中保温一段时间后,甲、乙试管中加入适量的双缩脲试剂,丙、丁试管中不加任何试剂。对实验现象的预测正确的是
跳远金牌应该给____,银牌给____,铜牌给____.
— I didn't see you yesterday.
— ______ I was ill yesterday, ______ I didn't go to work.
After the quarrel, I tried to fix the misunderstanding between us, but all my efforts seemed ______.