—I didn't go to bed ________ 12 o'clock last night because there was too much homework.
A:until
B:though
C:after
D:beside
— Sorry, I must ______ the piano now.
某生物的卵细胞中有6条染色体,其中来自这个生物父方的染色体( )
1980年,我国在深圳、珠海、汕头和福州建立四个经济特区,打开了对外开放的突破口.
错误: ____ ;
订正: ____ .
某同学在探究性学习中收集了下组图片,该组图片信息所反映的历史主题是( )