1·At the outset, it seemed necessary to be on guard against the other two.
一开始，似乎有必要提防另外两个。
2·We should be on guard against such people.
我们应警惕这种人。
3·We must be on guard against hidden enemies.
我们必须警惕暗藏的敌人。
4·Always on guard against shadowing submarines.
时刻警惕跟踪的潜艇。
5·We have to be on guard against information theft.
我们必须警惕反对信息偷盗。
6·We should be on guard against the enemy's invasion.
我们要防范敌人的入侵。
7·Be on guard against those who are jealous of your success.
要提防那些嫉妒你的成功的人。
8·Thus, you should be on guard against this confused mapping.
因此，您应该谨防这种有混淆的映射。
9·Consumers should always be on guard against credit card scams.
消费者必须经常提高警觉，以防各种信用卡诈骗。
10·Cowboys should be on guard against the attacks from wild animals.
牛仔必须提防着野兽的袭击。