"热心热忱"用英语可以表示为"enthusiastic"或"zealous"。
"Enthusiastic"是由希腊语"enthusiasmos"演变而来，原意为"充满热情"，后来逐渐演变为指"热心的"、"热情的"的意思。
"Zealous"来源于希腊语"zelos"，原意为"热心"、"热情"，后来逐渐演变为指"热心的"、"热情的"的意思。
下面是一些例句：
She is an enthusiastic supporter of the team. (她是这支队伍的热心支持者。)
He is always zealous in his work. (他总是在工作中非常热心。)
The teacher was enthusiastic about her subject and it was contagious. (老师对自己的科目充满热情，这种热情很容易传染。)
The young man was zealous in his efforts to help the community. (这个年轻人在为社区做贡献方面非常热心。)