Translation:I need to be at the hospital by four o'clock sharp.
Ultimately I feel there is a clash here. In English, if you include 'sharp' you are indicating a precise time, 'by' indicates anytime prior and is therefore in contradiction with concept of 'sharp'. Please Duo, if you read these, choose one or the other, as both in the same sentence doesn't work in English.
Is this learning English or learning Chinese? How is "At 4pm sharp I want to arrive at the hospital" a wrong translation? The English grammar is right and the translation is just "need to be" vs "want to arrive", but its perfectly ok in English to say " I want to arrive somewhere by 4pm sharp..." and that's exactly how Chinese say it. SMH...
Yes, this is because there are times when 到 is used to indicate "arriving" someplace to do something and we just don't say "I'll arrive at the airport to get you" but rather "I'll go to the airport to get you". However the stress is on "arriving/ being at" vs "moving toward/ going"