Both C and D are correct answers. "did Yao Ming expect" - "Did" makes this an event in the past. UNTIL a moment in the past, I could have said something IS true. So, before that moment you could have said "Little does Yao Ming expect.....", and you would have been referring to the present at the time you made the statement. "had Yao Ming expected" - "had" and "expected" make this a past event. This is more like double "in the past". AT a moment in the past, I could have said something WAS previously true in the past. So, at that moment in the past, you could have said "Little has Yao Ming expected..." and at the time you made the statement you would have been referring to the past Either way, in the past up until some moment, Yao Ming did expect the backetball to be sold at that price. The moment is not specified, but this was true until that moment. For example, you could add "until I told him" or "until it was actually sold" to this sentence to specify the moment it changed. Furthermore, something does not HAVE to happen for "could" to be used. That is, something that COULD happen is true long before it DOES happen, and may not happen at all. "....could be sold for 150,000 Yuan at the auction." This has been true ever since someone decided to sell the basketball, even though we did not KNOW it was true. You could say it has always been true because it refers to a future event, "the auction". It would be like saying "I could go to the beach tomorrow". This is true today, even though tomorrow is not here yet. This is all assuming that "the basketball he once played..." is correct, even though it is not, and it should be reworded as Claire commented.

The reason lies in the selling of the basketball. Since it was sold at THE auction, the basket ball was sold in the past, so the expectation was "more than the past", i.e. past perfect. It would be different if the basketball was being sold at AN auction. Little did Yao expect his basketball would be sold at AN auction. These are the very subtle difference of advance English. Your test here is clearly an advanced test.

Because there are 2 actions in the past: Selling the ball and his expectations and obviously his expectation took place before selling the ball. The past perfect tense is thus used for the action happening first in the past.

Because the time when he expected ocurrs in the past, i.e. before the auction, then if you're talking about something that happened in the past before another action, you have to use past perfect tense. For example: The ball sold for 150,000, he had little expected it .... (or he hadn't expected it) The expectation occurs before the sale.

I'm sorry, I've made a mistake. A correct answer is B. You have to use the Past Perfect Time (serf the internet, if you don't know it) because the time of his expectation ocurres before the action of sale of the ball. Firstly he had expected and the ball was sent after it. Examples: He won the competition, because he had trained a lot during the previous year. I just don't like the word order in the "D" variant. Adjective-auxiliary verb-subject-the main verb. That sounds strange