脑脓肿壁形成早期，CT表现为（）。
A.水肿最明显
B.结节样增强
C.不均匀环形增强
D.均匀环形增强
E.无水肿
参考答案：D
Our school is having a sports meeting. Someone _____ here already. [ ]
A. arrived
B. have arrived
C. has arrived
如图，请根据通电螺线管左端小磁针静止时的指向，标出螺线管的S极、磁感线的方向及螺线管圈中的电流方向．
