他必须跟进补上自己的飞行时数，还得通过一系列的考试。

He needs to keep up his flying hours and there are some exams to get through.

youdao

他在本月一份报告中写到，这意味着中国对美国国债的胃口会缩小，因此要想美国利率不升高的话，其他购买者必须跟进补缺。

'this means its appetite for U. S. debt will be smaller,' he wrote in a report this week, so other buyers will have to pick up the slack if interest rates aren't to rise.

youdao