Q: About wedding, 婚禮上祝賀的話: 如新婚愉快, 白頭偕老...

A: 婚禮是人生大事. 在美國由男女雙方家長一起策劃一切事宜, 雖然費用是由女方負擔. 新娘穿結婚禮服戴面紗; 新郎及伴郎穿燕尾服. 來賓也盛裝出席. 婚禮完後, 所有受邀來賓參加為新娘新郎舉行的酒會. 這時受邀的賓客會輪流走到新婚夫婦以及他們的家長所站的 receiving line 前向他們道賀.
Weddings are festive times in the United States. The two families plan the wedding and reception together, although the bride's family generally pays for the wedding. The bride wears white gown and veil, and the groom and his attendants wear tuxedos. Guests dress up to the service and reception. After the wedding service, the guests go to the reception party held for the newly wed. A receiving line is made up of the bride and groom and their families. Guests pass from person to person in the receiving line to give their congratulations and good wishes.
這時妳可以說一些恭賀的話:
Best wishes for years of happiness for two of you.
We wish you a long-lasting happy marriage.
I wish you much happiness together. Congratulations and
    happy marriage to you.

The two of you make a perfect couple. (
一對佳偶)