—It's already 7:50. If you want to get to the meeting on time,you must ______,Jack.
—I see. I'll walk quickly.
hurry up 快点；ring up 打电话给；stay up 熬夜。根据答语中的 I'll walk quickly（我将很快地走）可知上句应用 hurry up。故答案为 A。
Our school has ______ a sign at the gate,saying "Greet your child with a smile,not a mobile".
句意：我们学校已经在大门口树立了一个标牌，写着“微笑着向孩子问候，而不是用手机”。sign 意为“标牌”，与其搭配的是 put up “搭建；张贴”；put off 推迟；put on “穿上；上演；长胖”；根据题意，A项符合题意。
—What 's the meaning of "One Belt One road"?
—Let me ______ the words in the new dictionary.
句意：——你知道“一带一路”什么意思吗？——让我在新字词典里查一下这些单词。look at 看一看；look for 寻找；look after 照顾；look up 查阅。故选 D。