由于网络问题，视频会议的画面总是比声音慢半拍。

The video in our conference call ___lagged behind the audio due to poor internet connection.

他的手机在玩游戏时开始卡顿。

His phone started to ___lag when playing games.

他的电脑太旧了，运行程序时总是反应迟钝。

His old computer always ___lagged when running programs.