Question

plan用法

Answer 1

plan sth. 计划某事，后接名词
plan to do sth. 计划去做……，to是动词不定式，不是介词
plan for sth. 关于……的计划，plan是名词

Answer 2

用作动词
plan to do sth = mean to do 计划干。。。，打算干。。。
如，I plan to plant some vegetables in the garden
had planned to do 本来计划干。。。
如I had planned to water the vegetables yesterday, but there was no water in the well
用作名词make a plan to do sth

Answer 3

plan to do sth
make a plan to do sth

Answer 4

plan加to do