php输出html问题

Question

echo "<ul style='"display:block;"' id='ul_".$pid."'>".vbcrlf;提示这句话缺少，或者； 请问错在哪里了

Answer 1

echo "<ul style='display:block;' id='ul_".$pid."'>vbcrlf";

Answer 2

echo "<ul style='display:block;' id='ul_{$pid}'>vbcrlf";

Answer 3

echo "<ul style='display:block;' id='ul_{$pid}'>vbcrlf";//如果vbcrlf是变量前面加$