在实际工作中，NPN型三极管和PNP型三极管可直接替换。
参考答案：错
I bought a pair of running shoes because I want to _____ the teachers’ relay race.
A．join
B．take part in
C．in
D．have part in
隧道爆破是交通建设的重点和关键工程，试述钻爆开挖法通常有哪几种？
