“在白天”的英语可以翻译为：y day，by daylight，days ...

机器在白天隆隆地响个不停.The machines roar incessantly during the hours of daylight.那仪器是在白天飞越水域时使用的.The instrument is used when fly overwater in the daytime.展览在白天和晚间开放.The exhibition will be opened day and evening....