The adverbs deep and deeply can both mean 'a long way down or into something'. Deep can only mean this and is more common than deeply in this sense. It is usually followed by a word like into or below.副词 deep 和 deeply 均含由上到下或从外到里距离大的意思。deep 只含此义，而且用于此义时较 deeply 常用，其后通常接 into 或 below：◆We decided to go deeper into the jungle.我们决定继续深入丛林。
Deeply usually means 'very much'. * deeply 常含非常之义：◆deeply in love深爱◆deeply shocked大为震惊 You can use deep down (but not deeply) to talk about a person's real nature.表示人的本性、心地可用 deep down（但不能用 deeply）：◆She can seem stern, but deep down she's a very kind person.她可能看上去严厉，其实心地非常善良。◆She can seem stern, but deeply she's a very kind person.