Modal Verbs (would / should)?

1. In a French restaurant, if you like any dish (I think that) you "should" send for the chef and congratulate him, and if anything is wrong (I think that) you "should" send for the manager and complain.
條件句是「不真實的」想定時，才用「假設語氣」動詞(即用：liked +was wrong)（但這樣的狀況不合情理：即我知道你根本不喜歡法國餐廳的食物，而且我知道任何餐廳都不可能出差錯。）。
但這裡的條件句應該用「直述語氣」才合理，因為從說話者的角度來看，兩個條件都是「現在及未來有可能發生」的狀況（即用現在簡單式的like + is wrong)。主要子句助動詞should的意思在表示：我認為你「應該」（這是我的看法）。不能用表示「你願意」的would（我怎麼能決定你的意願呢？）。

2. If the electric starter "should" fail, you can make use of the handle bar to start the engine.
條件句是不真實的想定，因為說者認為「不會」發生這樣的狀況。動詞用「假設語氣」。而起動馬達為「物」，不會有意願，所以只能用should（未來將發生），而不能用有意願意義的would。結果句是真實的狀況，所以動詞用「直述語氣」。

3. I am surprised that you "will" ask the teacher to give you a higher grade.（事情即將發生:用未來式）
I am surprised that you "have asked" the teacher to give you a higher grade.（事情已發生：用現在完成式）
此句不能用should/would

(a)
i) Use WOULD to talk about "UNREAL/ UNLIKELY SITUATIONS". (不真實 / 很少會發生 的情況)
As in :-
3) I am surprised that you WOULD ask the teacher to give you a higher grade.
　[ 用 WOULD -- ∵ 「問老師給予 a higher grade」 是 幾乎不會 甚或 不可能發生 的 事 ]

ii) Use WOULD YOU LIKE to make POLITE OFFERS (有禮貌的 提議 /提供)
As in :-
1) In a French restaurant, if YOU LIKED any dish you WOULD send for the chef and congratulate him,
__________________________________________________________________________________________
(b) Use SHOULD for advice / suggestions.(忠告/意見)
As in :-
1) . . . . . if anything was wrong you SHOULD send for the manager and complain.
　[ . . . .如果有什麽不妥的地方, 你 「應該」send for the manager and complain. ]

2) If the electric starter SHOULD fail, you can make use of the handle bar to start the engine.
　 ( 倘若 電動開機制 (真的) 失效, 你可以 用手動制 to start the engine.)
[ "If the electric starter fails" 引伸到 一 SUGGESTION : make use of the handle to start the engine.→ ∴ 用 SHOULD ]

★★ : 本來, "the electric starter fails" is an UNLIKELY SITUATION,
∴ 可以寫 : "If the electric starter WOULD fail, you can make use of the handle bar to start the engine."
但 "the electric starter WOULD fail" 就像把 electric starter 這物件「人物化」, 不太合理, 所以不選 WOULD！

(1)would send---polite offering--modal verb
---should in contrast with would to suggest as auxiliary verb as adv cl.--wrong here
---You" should" send for the manager and complain----for advice and suggestion.
(2)should---future in supposition with "if" wording to suggest;
---would is too humanized by the will-minded.
(3)would=unreal world; unlikely situation.If likely should use should most likely !!!
----used with the "you" to form a conditional statement expressing your will or intention, expresses ----obligation or compulsion that you should ask the teacher for a higher grade:-
Hence:-I am surprise that you "should" ask the teacher for a higher grade.

1. In a French restaurant, if you liked any dish you would send for the chef and congratulate him, and if anything was wrong you would send for the manager and complain.

2. If the electric starter would fail, you can make use of the handle bar to start the engine.

3. I am surprised that you should ask the teacher to give you a higher grade.