- do I need to feed the pet dog?
- Twice a day.
A:How long
B:How much
C:How soon
D:How often
西瓜在夏天深受大家欢迎。挑西瓜首选表皮光滑,花纹清晰、明显,两端匀称,四周饱满的。除了外观,①____,绿色瓜柄的西瓜比较熟;横切开瓜柄,②____,白色范围越大越成熟。③____,声音比较沉闷的瓜比较熟。