---What did our teacher do?

---He raised his arm as a(n)        for us to stop.

A．signal

B．advice

C．evidence

D．design

粪便隐血试验为阳性常见于()

A．消化不良

B．消化道出血

C．胃溃疡、胃炎或胃癌

D．十二指肠溃疡

E．肠糜烂