When summer comes, the weather becomes __________ and the flowers become __________.

A．hot and hot; beautiful and beautiful

B．hotter and hotter; more beautiful

C．hotter and hotter; more and more beautiful

D．hotter; more beautiful and more beautiful

机械式空气悬架系统主要由哪些部件组成（）。

A、气囊总成

B、高度控制阀

C、减震器总成

D、高度传感器