（）在腌制时对肉起呈色和防腐作用。
A、抗坏血酸
B、磷酸盐
C、硝酸盐
D、发色剂
参考答案：C
He said that not until the heavy snow blocked the express _________ how serious the weather was.
A．did the tourists realize
B．the tourists realized
C．the tourists did realize
D．didn’t the tourists realize
小儿出生后主要造血场所是
A．肝脏
B．骨髓
C．脾脏
D．淋巴结
E．胸腺
