tenses & verb form

Hi,
1) The sky was still dark though the sun was rising slowly at that particular moment.
(為什麼用 was rising, 請解釋)
The reason why we use the past progressive tense here is that
the sunrise was in action ( in the past) . ( not a state, but an on-going action in the past)
2) Past perfect tense is used here.
It is because you had=已經 set your alarm clock and you've forgotten the whole thing.
We state " setting my alarm clock"<---- this event happened previously.
Example:
I went to watch the show. We had discussed it in class.
Here we KNOW that the discussion took place FIRST -- even though the sentence describing it comes afterwards. We discussed the show, and THEN I went to watch it. This can be very useful when you are telling a story or relating a sequence of events. At any point in your story, you can jump BACK to a previous event, but your reader will not be confused.It is because the past perfect tense will make it clear that the event happened previously.
3) I turned and switched off my alarm clock so as not to wake up other members of my family. (為什麼用 to wake, 請解釋)
Ans: " so as to" 以便 is a phrase.( positive)
" so as NOT to" is negative .
That's why we say " so as not to wake (VERB)...........".

Hope you understand it more.
ByeO_O

Please refer to the following examples.
1) The door bell rang when I was having dinner.
This tells that the duration of one action is different from the other. I was
having dinner before the bell rang, the dinner still continued after the bell
rang. This is used to describe past action and past continuous action.

2)When I arrived at the station, the train had already left. The cat had already eaten the fish on the table, when I came home.
This describes that one action happens earlier than the other. This is used to
describe actions happened in the past.

3)I wake up early so as to see the sunrise. I studied hard so as to pass the
examination.
"so as to see" and " so as to pass" are adverbial infinitive phrases to qualify
the verbs "wake up" and "studied hard" respectively.
I wake up early. My purpose is to see the sunrise.
I studied hard. My purpose is to pass the examination.

1) The sky was still dark though the sun was rising slowly at that particular moment.
(為什麼用 was rising, 請解釋)
Sunrise continues for some time.
This is why past continous tense (was rising) is used in the sentence.

2) I realized that it was only six thirty. I had set my alarm clock to ring the night before because I have probably forgotten that it was a holiday the next day.
(為什麼用 had set, 請解釋)
The event of setting my alarm clock happened before the past event of realizing...
This is why past perfect tense (had set) is used here.


3) I turned and switched off my alarm clock so as not to wake up other members of my family. (為什麼用 to wake, 請解釋)
This sentence belongs to the pattern in which the verb is followed by 'to-infinitve of purpose'. i.e. Subject + verb(intransitive) + to-infinitive.
This is why 'to wake...' is used as' to-infinitive of purpose'.