若 $\theta \in \frac{\pi }{4},\frac{\pi }{2}$ ， $\sin 2\theta =\frac{3\sqrt{7}}{8}$ ，则sinθ=（   ）

①意为悲伤;悲痛。____

②忧愁悲伤。____

③太阳和月亮像穿梭一样地来去。形容时间过得很快。____

④受到的启发或益处很大。____

语法填空。阅读下列材料，在空白处填入适当的内容（不多于3个单词）或括号内的正确形式。   

    Long ago in a small, faraway village, there was a place ____ (know) as the House of 1000 Mirrors. A small, happy little dog learned of this p____ and decided to visit. When he arrived, he jumped happily up the stairs to the doorway of the house. He looked through the doorway with his ears lifted high and his tail wagging as fast as it ____. To his great surprise, he found himself ____ (stare) at 1000 other happy little dogs with their tails wagging just as fast as ____ (he). He smiled a great smile, and was answered with 1000 great smiles just as warm and friendly. As he left the House, he thought to himself, "This is a wonderful place. I ____ (come) back and visit it often."

    In this same village, a____ little dog, who was not quite as happy as the first one, decided to visit the house. He slowly climbed the stairs and hung his head low as he looked into the door. When he saw the 1000 ____ (friendly) looking dogs staring back at him, he growled(咆哮) at them and was horrified to see 1000 little dogs growling back at him. As he left, he thought to himself, "That is a horrible place, and I will never go back there ____."

    All the f____ in the world are mirrors. What kind of reflections(反映) do you see in the faces of the people you meet?