已知双曲线x2-y2a=1的一条渐近线与直线x-2y+3=0垂直，则a=____

选择方框中词的适当形式填空。（5分）

小题1:His face seems very ______ to me, but I can’t recognize him.

小题2:The meeting ______ for 3 hours and many people got bored.

小题3:The doctor asked the man to eat ______ because his stomach was seriously bad.

小题4:It’s _______ to throw away the things that can be reused.

小题5:He runs as ______ as possible to catch the bus.

项目的全生命周期

在“间距”选项区可进行文字的______、行间距、______的设置。

驾驶机动车在道路上违反交通安全法规的行为属于违法行为。

下面哪一种灌水方式不属于微灌的范畴。（）

A、微喷灌；

B、滴灌；

C、涌泉灌溉；

D、膜孔灌