The? (question mark) literal in the statement string is a parameter marker that represents the variable in which the result is returned.

语句字符串中的？(问号)是一个参数标识，代表用来返回结果的变量。

youdao

The question mark (?) represents a parameter marker.

问号（?） 代表参数标记。

youdao

This is why timing the mark is so important in dog training and why marker training is so effective.

这就是为什么训犬时标记的时机是那么重要，为什么响片训练是如此有效。

youdao

The Merck study "showed a real question mark in the therapeutic marker, " said Roger Newton, chief science officer of drug firm Esperion, and a discoverer of Lipitor.

WSJ: New Rules for Boosting Good Cholesterol

On the half-hour mark Sergio Busquets rifled a shot at goal, which fell to Villa who spun his marker and shot from close range.

BBC: Euro 2012 qualifiers: Scotland 2-3 Spain