To swim properly, a course of instruction is necessary.
举一反三
- 中国大学MOOC: To swim properly, a course of instruction is necessary.
- It's usually necessary for you to dress properly for a formal dinner party.
- The freight forwarder would prepare all necessary documents for exporter if necessary．
- All the risks should be calculated in advance.This is necessary.可改写为：It is necessary that all the risks should be calculated in advance.
- Column headings of a table consist of headings that identify the items listed in the columns below them, subheadings as necessary, and units of measurement as necessary.