根据题意与分析可得：
398接近400，相差2；
所以，A+398=A+400-2．
故选：B．
The famous basketballer, _______ tried to make a comeback, attracted a lot of attention.
A．where
B．when
C．which
D．who
铝镁合金焊接时，常采用含镁量比母材（）的焊丝。
