刀具刃磨后，刀面越平整，表面粗糙度越小，刀具寿命就越长。
参考答案：对
One of the collectors collected some seeds from a tree that had _____ him.
A．interest in
B．appealed to
C．been attracted
D．drew attention of
G菌与G菌细胞壁共有的组分是（）
A.肽聚糖
B.磷壁酸
C.外膜
D.脂多糖
E.核心多糖
