cheerful指“乐观愉快天性的自然流露, 包括在不利或令人不快的情况下保持愉快心情”, 如:He always looked cheerful even in defeat.他总是高高兴兴, 即使在输了的时候也是如此。glad 指“由于某一特定事情或原因而高兴的”, 如:“I'm very glad to have such a chance to go abroad.我很高兴有这次出国机会。joyful指“一种外来事件使情绪强烈、起劲、愉快的”, 如:They were singing and dancing to celebrate this joyful occasion.他们唱着、跳着庆祝这令人欢乐的时刻。joyous 指“性情或气质上快乐的”, 如:a joyous family快乐的家庭。