题目内容：
回答题One Sunday morning, Millie and Amy went to Sunshine Park. They love to chat there. As usual, they sat 16 a big tree. Suddenly, they heard a whistle from the bushes behind the tree.
They turned around but could not see anything unusual. They were 17 .
"Is 18 there?" Millie asked. Nobody answered. They 19 very. carefully and heard the strange noise again. The two girls were very afraid. They ran away quickly. On their way, they met Andy.
"What happened?" Andy asked. "There's a ghost in the 20 . Please help us. " Millie said. "Really? Tell me more. " Andy said. Millie told Andy everything. Andy went to the park, 21 beside the tree and listened carefully. Then he heard 22 noise! He looked behind the tree and heard another whisper. He was now sure the sound 23 from the bushes. He searched carefully.
"Oh! Here it is. " Andy said to himself. He 24 a little cat in the bushes. It was very weak. When it miaowed, 25 made a sound like a whisper.
16. __________ A．under
B．on
C．behind
D．in
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