问题补充：
.Emergency line operators must always calm and make sure that they get all the information they need to send help.
A. grow
B. appear
C. become
D. stay
答案：
A. grow
B. appear
C. become
(答案→)D. stay
解析：stay意为“保持”,stay calm表示“保持冷静,镇定”。根据所提供的情景“make sure that they get all the information they need to send help”可判断出急救中心的接线员必须保持镇静,确保得到他们需要的全部信息,以便派送人们进行救护。grow 意为“渐渐变得”；appear 意为“显得,好像”；become 意为“变成,成为,转为,变得”。
