He was mimicking the motion of a machine gun firing.

他模仿着机关枪发射的动作。

youdao

He thought he heard a gun firing in the distance, but he couldn't believe his ears.

他认为自己听到了远处开枪的声音，但他不敢相信自己的耳朵。

youdao

She thought she heard a gun firing in the distance, but she couldn't swallow her ears.

她认为自己听到了远处开枪的声音，但她不敢轻信自己的耳朵。

youdao

But in nineteen eighty-eight, he was charged for firing a gun that he did not legally own.

VOA: special.2009.11.01

Heavy artillery shelling and machine gun firing were heard and seen over the Homs neighborhood of Khaldiyeh, she said.

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The Warbeast uses two LEGO Technic motors to keep the gun firing at a constant rate, but the other guns in the book are powered by nothing but rubber bands and physics.

FORBES: Badass LEGO Guns: The Book Sells Itself

Switching on radar, or an anti-aircraft gun firing a single salvo, now brings down a hail of bombs on anything deemed threatening, from command bunkers to radar stations, and even anti-ship missiles.

ECONOMIST: Why the bombs are falling on Iraq