阅读所给短文, 并根据文章后的题目要求进行简答。
[1] Of the fruits of the year I give my vote to the orange. In the first place it is available if not in actual fact, at least in the greengrocer’s shop. On the days when dessert is a name given to a handful of chocolates and a little preserved ginger, then the orange, however sour, comes nobly to the rescue; and on those other days of plenty when cherries and strawberries riot together upon the table, the orange, sweeter than ever ,is still there to hold its own. Bread and butter, beef and mutton, eggs and bacon, are not more necessary to an ordered existence than the orange.
[2]  It is well known that the commonest fruit should be also the best. Of the virtues of the orange I have no room fully to speak. It has properties of health giving. It is clean, for whoever handles it, he doesn’t eat it directly but handles its outer covering, its top coat, which is left in the hall. It is round, and forms an excellent substitute with the young for a cricket ball. But all this would count nothing had not the orange such delightful qualities of taste. I dare not let myself go upon this subject. I am a slave to its sweetness.
[3] Yet with the orange we go live year in and year out. That speaks well for the orange. The fact is that there is an honesty about the orange which appeals to all of us. If it is going to be bad and it begins to go bad from the outside, not from           . How many an innocent-looking apple is harboring a worm in the bud. But the orange has no secret faults. Its outside is a mirror of its inside, and if you are quick you can tell the shop man so before he slips it into the bag.
What’s the main idea of this passage? （no more than seven words.）
                                                                          
List at least two virtues of the orange? （no more than six words.）
                                                                          
Fill in the blank in Paragraph 3 with proper words? （no more than two words.）
                                                                          
Why is the orange clean? （no more than seven words.）
                                                                          
What does the word “it” (Line 2 , Paragraph 3)probably refer to?（no more than two words.）