重點“could have ～ed“ 在英文裏意思 you were able to do, but didn't do。 你能做，但(實際上)並沒有做.
唉，給你舉個例 “You could have passed the test （=You were able to pass the test, but you didn't. 翻譯：你（本或許能夠）通過測試，但你（實際上）並沒有通過)
而具體到那句“we are “72 hours into the diagnosis,” meaning the president could have tested positive as early as Wednesday”後半句是對“72 hours into the diagnosis,”的進一步解釋說明，
意思是總統早在周三或許可檢測出陽性，but the president didn't test。總統（實際上）並沒有檢測，假如若檢測了其結果或陰或陽。醫生推測，若周三做了檢測結果可能會是陽性。就是說周三時並沒做檢測，更不要說確診。
明白理解了沒啊? 英文水平有待提高咯 :) 英文與中文是不同語言係統，語法和講話思維也不同，直譯會鬧大笑話。
