由树木活的枝条形成，节子与周围木材紧密连生，质地坚硬，构造正常，这种节子称（）。
A、腐朽
B、漏节
C、健全节
D、活节
参考答案：D
This is only a solution that can be adopted to solve the problem , so you have to find a better way.
A．individually
B． definitely
C．temporarily
D．continually
1755年康德提出的星云假说认为原始星云是一团炽热的气体。
