keep up appearances

maintain an impression of wealth or well-being, especially to hide the true situation

（尤指為了掩飾真實情況而）維持門面，裝門面，裝體面

make (或 put in) an appearance

attend an event briefly, especially as a matter of courtesy

（尤指出于禮節而）短時間到場，露面，亮相

to (或 by) all appearances

as far as can be seen

就表面看來，就所能看到的情況而言

to all appearances, it had been a normal day.

表面上看，那是平常的一天。