sharing可以是分享吗:“He wondered if he had bitten off more than he could chew" what's meaning?

“He wondered if he had bitten off more than he could chew" what's meaning? He wondered where to buy the stamp? If he _____busy tomorrow, he will come. He’s eighty if he’s a day If he love me演唱者是谁？ if every man says all he can I asked him 后面是跟if he can 还是if he could? He has never traveled in any big cities, but he talks about London as if he ___ there. He knows little about the city as if he ______there so far. He exceptional as if he were a millionaire, spending money left, right and center.