A. People throughout the country have greatly demanded all kinds of nutritious food.
B. There is a great demand across the country for all kinds of nutritious food.
1. 以形容词或形容词组开头 如：①Mary was very pleased and telephoned her mother．→Pleased，Mary telephoned her mother．②The girl，hungry and thirsty，went back home．→Hungry and thirsty，the girl went back home．
2. 以副词开头 如：The child stayed there quietly．→Quietly，the child stayed there．
3. 以不定式开头 如：He got up very early to catch the bus．→To catch the bus，he got up very early．
4. 以现在分词或过去分词开头 如：①I was filled with anticipation when I came home from school that dark winter's day so long ago．→Coming home from school that dark winter's day so long ago，I was filled with anticipation． ②If you give me enough time，I can do it well．→Given enough time，I can do it well．
5. 以介词短语开头 如：Chester like many other adventurers had experienced fear and conquered it．→Like many other adventurers，Chester had experienced fear and conquered it．
6. 以同位语开头 如：Sue，our monitor，always likes giving suggestions to everybody．→Our monitor，Sue，always likes giving suggestions to everybody．
7. 以从句开头 如：①Francis had already surprised his friends several times before he sailed round the world single-handed．→Before he sailed round the world single-handed，Francis had already surprised his friends several times．②You will greatly improve your finished product if you have a quality control inspection．→If you have a quality control inspection， you will greatly improve your finished product．