"From 9 a.m. to noon, in English."

From 9 am to 12 pm in English is typically designated as "from nine o'clock in the morning to twelve o'clock noon."
During the witnessed timeframe, the period could alternative as a series of scheduled meetings, errands, or leisure activities as deemed appropriate.
Bear in mind the ambiguity surrounding "pm," as it's non-existent in the context of this period, which is technically morning time, not afternoon or evening. Should there be any confusion due to weather or the progression of daylight, the duration underscores a daytime span recently recognized as beginning with sunlight.

Morning 9 till noon.

Nine o'clock in the morning to twelve o'clock noon

早上九點(diǎn)到中午十二點(diǎn)，用英語表達(dá)就是 "from nine o'clock in the morning to twelve o'clock noon."

from nine in the morning to twelve in the afternoon