1 . Lifelike shrimps play a key role in Qi’s vast body of visual artworks. The “shrimps” are so popular _______ they have become synonymous with the painter himself. (用适当的词填空)

2 . Some amateurs can perform at such a high level ________ even professionals sing high praises _________ them.(用适当的词填空)

3 . The food is ________ delicious that you don’t need much of it to make you happy. （用适当的词填空）

4 . Learning is ______a big problem that changing the way people do it will have a wave of secondary effects. (用适当的词填空)