图中肝脏图像最长的管道为()。
A.肝右静脉
B.肝中静脉
C.门静脉右支
D.下腔静脉肝段
E.门脉左支
参考答案:A
It has been proved ________ eating vegetables in childhood helps to protect you against serious illnesses in later life. [ ]
A. if
B. because
C. when
D. that
根系的三种趋性是向水性、()和向氧性。