When_____help, one often says" Thank you
题型：选择题
问题：
When _____ help, one often says" Thank you. " or "It's kind of you." [ ]
A. offering
B. to offer
C. to be offered
D. offered
When _____ help, one often says" Thank you. " or "It's kind of you." [ ]
A. offering
B. to offer
C. to be offered
D. offered