no less than

I studied.

私は勉強しました

I studied for no less than five hours.

私はなんと五時間も勉強しました

I studied for no less than five hours without a break.

私は休まずになんと五時間も勉強しました

I studied at the library for no less than five hours without a break.

私は図書館で休まずになんと五時間も勉強しました

I studied at the library yesterday for no less than five hours without a break.

私は昨日図書館で休まずになんと五時間も勉強しました