Item B means to enter a two-digit decimal integer, read a *, read a decimal integer and read a decimal long floating point number.
In item C, it means reading a hexadecimal integer into X, reading a decimal integer and ignoring it, and reading a hexadecimal integer into Y. ..
In item D, it means reading a hexadecimal integer, an octal integer and a floating point number. However, scanf () cannot specify the precision of floating-point numbers, that is, %6.2f error.