internal activity的用法和樣例：
例句
- The key to determining Mars's internal activity is given by quakes.
星震提供了確定火星內部活動(dòng)的線(xiàn)索。 - Pacific Valves' unique injector has a double ball check protection against leakage and a positive shut-off internal valve.
美國太平洋閥門(mén)獨特的注入器具有雙球止回保護，防止泄露，并保護閥門(mén)內部活動(dòng)部件。
