简述直排式琴弦的特点。
参考答案：
直排式钢琴，只有一根弦码，中、高、低音琴弦全部安排在同一根弦码上。缺点是不但体积较大，音响效果也不能令人满意。
根据括号中所给的汉语写出单词，使句子意思完整正确。
1. There is some ______ (水) in the bottle.
2. Mrs Jiang is good at ______ (唱) English songs.
3. Daniel is an active boy and he is crazy about playing ______ (足球).
4. The old man lives alone, but he doesn't feel ______ (孤独的) because he has many friends.
5. They wanted to remind us that we should protect the ______ (环境) by showing us the beauty of nature.
食用植物油的主要成分是（）
A.饱和脂肪酸
B.不饱和脂肪酸甘油酯
C.磷脂
D.饱和脂肪酸甘油酯
E.色素
