since和until可共用在一句嗎? 例如: Since yesterday, I've been learning English until I go to Japan next year.?

應該醬子寫才對:

Since yesterday, I have been learning English and will continue doing so until I go to Japan next year.

你的第2個問題的寫法有許多不好的地方:

1. than the previous day 是verbose.
因為: the tree has been inclined more steeply 就已經表示出"一直在"的意思.
而且,since yesterday就只有一天而已,怎摸會more XXX than the previous day?

2. inclined 被動用得不對. 因為樹 是有意志 行為的生物 應該用主動.

3. which 的使用不洽當. which 是 tree的關代? 還是 inclination 的關代?

4. 所以 應該寫成:

Since yesterday, the tree inclination has becoming more and more severe, which I fear will continue until the tree planter comes back.

5. 偶在我家的游泳池 旁邊也種了一些椰子樹. 有一顆 椰子樹 他也是一直傾斜 現在樹幹是有一半躺在石頭上面 長了10年了 我反而覺得 醬子 比較好看.

Since yesterday, I have been continuing to learn English prior to Japan. Yip

The present perfect continuous expresses actions which began in the past, extended up to now and may continue in the future.
Hence you have learnt English for 1 day and 1 month only.
eg:-I have been learning English (for one day) since yesterday,extended up to now, and "may" continue in the future (for one month) till I go to Japan next year.
--since, adv. with the perfect tense after a day between some time in the past and the present time.
--until , prep, conj--->till.
--hence adv and prep can be used in the same sentence.