The simple past
I cleaned
It began and completed in the past without any connection with the present
Similar words and expressions include:-today=this morning=(9:00-10:25 )am.
washing clothing=cleaning=cleaned (my room)
no" since" used;
Hence:-
I cleaned my room this morning.

早上九時開始洗衫直至十點，在早上十點二十五分我講

I cleaned my clothing this morning. - simple past tense 洗衣服

I have cleaned my clothing - present perfect time

my room = 我的房間

Direct speech
She said, "I am flying to the US today."
Report speech
She said (that) she was flying to the US that day.

2015-03-23 03:45:32 補充：
Frankly speaking, do you think it is correct (especially if written by me instead of copying from a dictionary)?

It has the grammar wrong and the meaning confusing.

She said she is flying to the US today. (correct in grammar and the meaning as well)

老實講, 我覺得有的怪.

首先, 你用 "today", today, 係包括到晚上零時為止既 24小時, 即係包括下午到晚上既 "未來" 時間, 咁用 cleaned 過去式, 就有的奇怪, 點解唔用 morning? 甚至係再精確的既時間?

另外, 你既然係只係洗衫, 就唔應該講 cleaned my room, 唔通你既衫就係你間屋? (呢度唔係挑剔, 有一首經典歌就叫 Street of Lodon, 就係講露宿者既, 其中有一句就係 "carrying her home into carrying bag")

所以, 如果你想講洗衫, 就簡單講 I cleaned my shirt this morning.

想講清潔間房, 就講 I cleaned my room this morning.

想講整理好間房, 就講 I tidy up my room this morning.

"I cleaned my room today." is ok
1. clean the room (整理房間) - 如果你將洗衫當成是整理房間的一項工作，用'cleaned my room' 係可以接受的，示乎你要幾詳情的描述。
2. 'Today' - 從午夜開始共廿四小時，這包括過去，現在和未來。你所描述的事情是發生在你說話時之前，所以pass tense係ok。

2015-03-21 18:13:20 補充：
似乎大家在比較緊"你今日食咗早餐未 vs 你今早食咗早餐未" 類似問題?
我自己就覺得兩者都可以，當然,"你今早食咗早餐未"係比較合邏輯D，但並不可說"你今日食咗早餐未"是錯的。只視乎說這話時的情況。

"洗衫" 和 "打掃房間"是兩件不同的事, 當然有問題
假設早上九時開始打掃房間直至十點, 仍然有問題
錯原因是用 past tense 在 today 上 ,
早上還未完, 下午, 晚上可能性再打掃房間

10:25 a.m. 應該講 "I have cleaned my room this morning".
~ the morning is not over yet.

下午, 晚上講 "I cleaned my room this mroning"

2015-03-21 09:04:53 補充：
"將洗衫當成是整理房間的一項工作", 我覺得怪,
不同房間衣服凌亂週處放, 執翻好整齊放回原處
"洗衫 " 和 "整理房間 " 可列入 domestic chores
10:25 am 我不會這麼早用 today, 尤其已經做了
我會用 this morning ~ more appropriate

晚上 Before I go to bed, 我會講
"I cleaned my room today."或者
"I cleaned my room this morning."

2015-03-21 09:11:43 補充：
TODAY

Past tense
She said she was flying to the US today.
晚上說 Did you get any letter today?

Present tense
I feel fine today.
Her son has not called her today. (~ up to now; Today is not over yet)

Future
早上早餐時說
He will appear in court today.

2015-03-21 10:08:05 補充：
發問者是否早上 10:00 已經做完打掃房間,?
today 餘下的時間不會做? 還是未做完, 可能下午繼續?
使用 this morning 是否比較好些 ? 至少時間 range 變窄了
recent action 可用 present perfect 最好不言及時間

2015-03-22 11:03:06 補充：
我現在講 "She said she was flying to the US today." ~ direct speech


"She said she was flying to the US today."
~ from MacMillan English Dictionary (2nd edition)

補充：

「清潔」一詞在中文只是形容詞，不是動詞。
http://www.fed.cuhk.edu.hk/~pth/pth_passage01.php?passage=156

但英文的 clean 則可作形容詞和動詞。

2015-03-21 02:31:27 補充：
哈哈哈, 我竟然中左招~

搞到亂哂龍~

真係唔好意思......

2015-03-21 02:34:32 補充：
Godfrey 請作答吧~

讓大家搞清楚事情...

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