The black people thus lay on the hard wooden boards, _________ stand up.

A new __________ bus service to Tianjin Airport started to operate two months ago. 

—Are you ______with doing a lot of homework every day?—Sometimes I am.But as a student，we have to do so at present.

-Life itself tells us it is necessary to learn to be     .One can hardly survive without help from other people in the world.

I know these flowers are not natural, but the _____ ones look more beautiful and can last long.