人类体细胞具有多少对染色体()
A．1
B．22
C．23
D．46
E．92
参考答案：C
--- Why does she always ask you for help? ----- There is no one else _______, is there?
A．who to turn to
B．she can turn to
C．for whom to turn
D．for her to turn
“512”汶川大地震后，灾区的防疫人员向水中加入一种消毒药片（其有效成分为NaClO）对水进行消毒．其反应原理为NaClO+X+H2O→NaHCO3+HClO，其中X的化学式为（ ）
A．CO2
B．H2O2
C．O2
D．CO
sk you for help? ----- There is no one else _______, is there?