Boolean that specifies whether the current thread blocks until after the specified selector is performed on the receiver on the main thread.

一个布尔值，指定是否阻塞当前线程直到指定选择器在主线程中执行完毕。

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The main rotary selector contact is always operated before the resistance contact (21).

主旋转选择器接触件总在电阻接触件(21)之前动作。

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Set the main switch selector to a (auto) or m (manual).

把主选择开关转到a(自动)或M(手动)。

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