已知下列负反馈系统的开环传递函数,应画零度根轨迹的是()。
①
<imgwidth="67"height="47"src="../uploadfiles/word/zdkzll002.files/image044.png">
②
<imgwidth="93"height="47"src="../uploadfiles/word/zdkzll002.files/image045.png">
③
<imgwidth="86"height="47"src="../uploadfiles/word/zdkzll002.files/image046.png">
④
<imgwidth="65"height="47"src="../uploadfiles/word/zdkzll002.files/image047.png">