The world needs to be on high alert.
世界需要高度警惕。
"They now seem to be on high alert, fully engaged and thinking creatively about what they can do and what is next," he said.
他说：“他们现在似乎要保持高度警惕，充分参与并创造性地思考自己能做些什么，未来会怎样。”
Experts still disagree over whether the vaccine caused cases to increase that year, and the C.D.C. will be on high alert for reports of it this year.
专家对这年增加的病例一直有不同看法和疾病控制中心对这年的报告保持警惕。
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