grammar有問題??

1. I ____ (NOT) tell him the bad news . ans 是 dare not 這裡用had better not 為何錯誤?My answer: 'had better not' is also correct. But if you are
asked to choose the best answer, maybe 'dare not' fits
the situation better.http://www.englishgrammarsecrets.com/hadbetter/menu.phpWe use “had better” plus the infinitive without “to” to give
advice. Although “had” is the past form of “have”, we use
“had better” to give advice about the present or future.The negative form is “had better not”. •You'd better not say anything.•I'd better not come.•We'd better not miss the start of his presentation. 2. The beaches in HongKong ______be much cleaner thirty years ago . ans 是used to 為什麼不是had better , 2個表達意思一樣?'had better' is wrong here as it is not about advice. The meaningsof 'used to' and 'had better' are completely different. 'Used to' means 'was true before but is not true now': The beaches in Hong Kong used to be much cleaner thirty yearsago. = The beaches in Hong Kong were much cleaner thirty years ago but now they are not clean. 3.He used to be a shy person and _________(NOT) talk in front of a large audience.ANS : didn't used to為什麼不用 daren't‘daren’t ‘ is correct in meaning but incorrect in grammar. If you want to use ‘daren’t’, it should be in the past tense => ‘dared not’

I hope you find the explanation useful.

2011-10-31 20:33:13 補充：
'didn't used to' is not wrong.
http://www.pearsonlongman.com/ae/azar/grammar_ex/message_board/archive/articles/00074.htm

3. He used to be a shy person and wasn't used to talking in front of a large audience.

The answer should be "wasn't used to" instead of "didn't used to" (wrong in grammar, anyway).

"be used to" (something / doing something) = to talk about something that you are familiar with so that it no longer seems new or strange to you 習慣於

e.g. She is used to hard work. 她習慣於艱苦工作。 (Yahoo)
We’re used to the noise from the traffic now. (Oxford)

Alternatively, "used to" (+bare infinite) is like a modal, used to talk about something that happened regularly or was the case in the past, but is not now. 過去一向, 過去時常; 過去曾(而現在不再)做 The negative form of "used to" is "didn't use to".