The board wanted to know（ ）the company was performing well.

The board wanted to know（ ）the company was performing well.
A、what
B、which
C、where
D、if
【正确答案】：D
【题目解析】：know后面缺少宾语，而从句中the company was performing well不缺主语和状语，所以可排除选项A，B和C；if在这里意为“是否”，引导宾语从句。