Tet is a national and (17)______ festival in Vietnam. It is an occasion for every Vietnamese to be reunited to think (18)______ their past activities and hope for good luck in the year to come. Before Tet, all houses are white washed and (19)______ with yellow apricot flowers and colourful lanterns. Everybody is looking forward to a more favorable life. On the New Year’s Eve, children are smartly dressed. They are hoping to (20) ______ money put in small red envelopes as they are wishing longevity to their grandparents and parents. Wrong doings (21) ______ be absolutely avoided on these days. A: summer B: traditional C: modern D: music