@Carl Love 

Thanks for your information, so it seems it's related to our computer's both hardware and software (operating system), as C_R said. We can hardly do something to solve it.

@C_R 

Totally agree.

Following is a screenshot from some other computer, it's also windows 10 with default windows font setting.

However, you can see it's quite well (mention again, SAME windows 10 default font settings...). And something interesting I found is that the font is even different with its windows display font, you can see the lower-case letter l(L) and capital letter I(i) are totolly different with us.

@Carl Love Yes, this phenomenon is so strange... Most fonts in maple is ok, but just only some places... I guess maybe it has something to do with java... (but in some other computer, I did see it does not have this issue)

@Carl Love  Wonderful.

BUT it cannot used to solve this kind of matrix equation "<<1, 2> | <1, 3>> . <c, d> = <a, b>", in other words, if the matrix is not square, the Solve can't solve it.

However, in Mathcad, it can be easily done as follows:

Don't know if mathematica can easily do this job...

Best Regrads,
Jankel