呼气性呼吸困难见于（）
A.肺气肿
B.白喉
C.支气管哮喘
D.异物
E.肋骨骨折
参考答案：A, C
常引起便血的结肠疾病是（）。
A.肠伤寒
B.Crohn病
C.肠结核
D.结肠息肉
E.急性肠炎
She can't help ______ the house because she's busy making a cake.
A．to clean
B．cleaning
C．cleaned
D．being cleaned
