It was until last year that he ___________.

A．left his hometown for a new start

B．came to realize the important of learning English

C．worked as an English teacher at a middle school

D．set out to build a new house of his town

导管输送的物质和输送的方向是（　　）

A．有机物，从上向下

B．有机物，由下向上

C．无机盐和水，从上向下

D．无机盐和水，从下向上