在邮寄前请密封信封。

Please ___seal the envelope before mailing it.

我的女朋友珍妮告诉我，她用颤抖的手指密封了信封，然后寄了出去。

Jenny, my girlfriend, told me that she ___sealed the envelope with trembling fingers and then posted it.

他用湿海绵安全地密封了包裹。

He used a wet sponge to ___seal the parcel securely.