Is there a way to easily determine we should use verb + ing after preposition "to"? e.g. The world is getting closer to achieving one of the most important public health goals of our time: eradicating HIV. Why "achieving" instead of "achieve" is used in the example above? Thank you in advance.

is there a difference when when we use adj. e.g. salty, bitter or sour to describe a person? e.g. Tom felt salty/bitter/sour when Mary got promoted.

Subject-verb agreement for money, time and distance? When we talk about a sum of money, a period of time or a distance as a subject, we use a singular verb. Does this grammar rule work for both American and British English?

Are there any easy way to identify uncountable nouns at first sight?

could you introduce funny ways of ending an email or letter? I realize that there are several words that we use in the end of a letter such as "regards", "love", "best". Are they any rules that we can follow when we use them? Except the ones that I mentioned, are there other funny ways of ending a letter? Thanks. Kelvin

When should we use past perfect tense in a sentence? Set grammar books aside, are they any situation that can easily remind us of using past perfect tense in sentences? Have a good day. Kelvin

20161027 Nazi secret base in the Arctic (part 1) 俄媒報導，俄羅斯科學家表示，在北極圈附近發現德國納粹在二戰時期遺棄的秘密基地。該基地距離北極圈約1公里，位於俄羅斯亞歷山大地島(Alexandra Land)。 Russian media reported that Russian scientists discovered an abandoned secret base of the German Nazi during World War II near the Arctic. The base is about 1km from the Arctic Circle, located in Alexandra Land in Russia.

How do we use "Dare"? For instance, if I am challenging someone who does not brave enough to hold a snake. Which one is correct below? I dare you not to hold this big snake. or I dare you to hold this big snake. Thank you in advance.

how and when do we use future perfect and future perfect continuous tenses? It seems that I have never used these two tenses before (probably because I do not know how to use it), so it would be nice if someone can tell me how and when we should use them? Thank you in advance, buddies.