泥石流是一股泥石洪流，爆发时间较长。经常发生在峡谷地区和地震、火山多发区，是山区最严重的自然灾害。()

A. hits
B. attacks
C. crashes
D. strikes

A. contribution
B. donation
C. reputation
D. credit

A. demanding
B. explaining
C. portraying
D. taking

A. positive
B. optimistic
C. active
D. negative