It was ________ he came back from Africa that year ________ he met the girl he would like to marry.

A．when；then

B．not；until

C．not until；that

D．only；when

木材的纤维饱和点是指木材的( )。

A．物理力学性质发生改变的含水率临界点

B．内部充满自由水和吸附水时的含水率

C．体积开始发生膨胀时的含水率

D．含水率影响其强度变化的最低临界值