Question

on these days/ in these days?

Answer 1

"On these days"
"in these days"
and "these days" are all grammatically correct
but carry different meaning.(1) these days: = nowadays
at the present time
now 当今，今时今日，现在这些日子 e.g.: People are more health conscious these days. (在这句，不可以说或写"in these days"
或 "on these days") (2) in these days: = during these days 在这段曰子里 e.g. August 1st to August 15 this year was the warmest period of the year. In these days the sale of air-conditioners was substantially higher. (3) on these days = on these (particular) days (在这些曰子里 (不一定是连续的) e.g. We usually eat at my parent's every sunday. On these days we would eat more than the rest of the week added together. Regarding tenses
for "these days"
use present tense
because it refers to the present time. For "in these days" or "on these days" use whatever tense that is appropriate for the "time" referring to. For example
in (3) above
if a "past" time is referred to
then the past tense will need to be used: "We ate at my parent's every sunday for the past 2 months. On these days we ate more than the rest of the week added together."
参考: encarta.msn/thesaurus_561598381/these_days
In These Days
参考: shrinke.im/a8VOd
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好似in these days顺口啲 ^^" these days有最近既意思
所以用present or present prefect会比较适合啲。
on these days/ in these days? Both are used in oral English. Both mean these days - for examples I have been very busy lately / recently/these days. no need to add in or on but people do not count your grammar during conversation so it does not matter. However
we better speak or write proper English whenever we could