【简答题】基因是_________中决定生物性状的小单位,由于基因位于染色体上,生物体细胞中染色体和基因都成__________存在,生殖细胞中染色体和基因都成________________存在。
【单选题】_______ Mr Dong is over 70, _______ he still looks very healthy. [ ]
【简答题】在各种生物细胞中,染色体的______、______和______都是一定的.
【单选题】为什么在反应釜中,用作氮封用途的氮气的作用是控制氧气,而不是控制燃料?
【单选题】— What do you think of your English teacher?— He is friendly to us although sometimes he looks .A
A.
— What do you think of your English teacher? — He is friendly to us although sometimes he looks ____. A. happy
【单选题】Although he eats ________, he doesn't looks ____________.