1_地上怎么乱七八糟的？ "的" often comes after adjective in Chinese and it is often omitted, especially in idiom of four words, to make phrases more simple and compact, such as “红花绿叶”，which people don't say "红的花绿的叶". For "的" in this question, you may also take it as a tone when people want to stress his intention of asking the question or express how surprising it is to see the messy floor, for example, "这件衣服怎么是红色的？我买的明明是白色的。" 2_ 真遗憾我没见到他。 “到” “了” “过” “着”， these four words often indicate the tense of a event. When a verb is followed by "到", it often means that you have reached the goal of that verb, so "见到" means you finally and successfully meet someone whom you missed or would love to meet so much. So here, since you didn't meet him, that's really a pity. 3_是大卫送给你的那个吗？ 是，那是他给我的生日礼物。 In China, people don't show their respect by changing the form of a verb as people use honorifics in Japan. "给" in Chinese can be used to say "give something to someone (either from the older to the younger or from the younger to the older)"; there is no difference. If you want to know why "送" or "送给" is not used in the second sentence. In my opinion, "送给" “送” “给” are showing subtle change of feeling about how important and meaningful the gift is to a person. when people say "送给", it is more formal than the others and "给" often used in daily life is the most causal one.