appear to be表示给人什么印象.
show是“显示”的意思,不过后面不能接不定式“to be mad”;
imagined意思是想象,不合题意.
thought是认为,这里明显意思不对,要么就写成别人认为他疯了,主语不应该是he.appear tobe具体怎么用 给个例子show 又是怎么用的例句：She appeared to be in her late thirties. 她看起来三十多岁。They appeared not to know what was happening. 貌似他们并不知道发生了什么。There appears to have been a mistake.似乎有一个错误。show有展现的意思：比如Show some respect, please!（请放尊重点！）