must

来自古英语motan,有能力做，有必要做，-st,过去分词后缀，来自Proto-Germanic*mot,能力，力量，来自PIE*med,测量，衡量，采取手段，词源同measure,medical.其在古英语时期语气并不是很强烈，后不断强化。比较noblesse oblige.

来自拉丁语vinum mustum,新酒，新酿葡萄酒，来自mustus,新鲜的，水灵的，来自PIE*meus,湿的，带水气的，词源同mist,moist.

must

must: English has three words must. By far the commonest is of course the verb, ‘have to’ [OE], which originated in Old English as the past tense of the now obsolete mūt ‘may, must’. It has relatives in German muss and Dutch moet, but its ultimate origins are not known for certain (there may be some distant link with Germanic ‘measure’-words, such as English mete, suggesting a semantic progression from an original ‘time measured out for doing something’, through ‘have time to do something’, ‘be able to do something’, and ‘be allowed to do something’ to ‘have to do something’). Must ‘unfermented grape juice for making into wine’ [OE] comes from Latin mustum ‘new wine’, a noun use of the adjective mustus ‘new’. Mustard is a derivative.

And the esoteric must ‘sexual frenzy in elephants, camels, etc’ [19] comes via Urdu from Persian mast ‘drunk’.
=> mustard

must (v.)

Old English moste, past tense of motan "have to, be able to," from Proto-Germanic *mot- "ability, leisure (to do something)" (cognates: Old Saxon motan "to be obliged to, have to," Old Frisian mota, Middle Low German moten, Dutch moeten, German müssen "to be obliged to," Gothic gamotan "to have room to, to be able to"), perhaps from PIE root *med- "to measure, to take appropriate measures" (see medical (adj.)). Used as present tense from c. 1300, from the custom of using past subjunctive as a moderate or polite form of the present.

must (n.1)

"new wine," Old English must, from Latin mustum (also source of Old High German, German most, Old French moust, Modern French moût, Spanish, Italian mosto), short for vinum mustum "fresh wine," neuter of mustus "fresh, new, newborn," perhaps literally "wet," and from PIE *mus-to-, from root *meus- "damp" (see moss).

must (n.2)

"mold," c. 1600, perhaps a back-formation of musty (q.v.).

must (n.3)

"male elephant frenzy," 1871, from Urdu mast "intoxicated, in rut," from Persian mast, literally "intoxicated," related to Sanskrit matta- "drunk, intoxicated," past participle of madati "boils, bubbles, gets drunk," from PIE root *mad- "wet, moist" (see mast (n.2)).

must (n.4)

"that which has to be done, seen, or experienced," 1892, from must (v.). As an adjective, "obligatory, indispensable," by 1912, from the noun; must-read is from 1959.

1. You must have noticed how tired he sometimes looks.

你一定注意到他有时候显得特别疲惫。

2. "His memory must be completely back, then?" — "Just about."

“这么说，他的记忆一定是完全恢复了？”——“差不多。”

3. There must be any number of people in my position.

一定有很多人处在我这种境况。

4. I must have driven past that place thousands of times.

我得有上千次开车经过那里。

5. "You must come to Tinsley's graduation party." — "I'd be delighted."

“你一定要来参加廷斯利的毕业聚会。”——“我很乐意。”