对于我们未能及时回复您的询问,我们致以诚挚的歉意。
We offer our ___sincere apologies for the delay in responding to your inquiry.
对于您宝贵的指导和支持,请接受我诚挚的感谢。
Please accept my ___sincere gratitude for your invaluable guidance and support.
董事会向所有志愿者的奉献精神表示诚挚的感谢。
The board extends its ___sincere appreciation to all the volunteers for their dedication.