①In order to protect our environment, we can't freely cut trees without the government's ____(允许)．

②There is no ____ (通路) to the street through that door.

③Humor is a more effective ____(防御) than violence(暴力)．

④Now that you are a college student, you should learn to be ____ (独立的)of your parents' help.

⑤Can you give me a ____(明确的)answer by tomorrow?

⑥With his new method, the time of the project will be ____ (缩短)．

⑦They brought the piano ____(斜着地) through the front door.

小明同学发现徐州市某楼房朝南窗户的正午阳光照射情况如图所示。据此回答下题。

某质点的运动方程是$S=\sin t$，则在$t=\mathrm{\pi }$s时的瞬时速度为  （   ）

李华同学平时不爱吃水果和蔬菜，结果导致他的牙龈经常出血，原因是他体内缺乏（　　）

命题“角平分线上的点到角的两边的距离相等”的逆命题是 ____.