完形填空
The day before Christmas I pulled into a store parking lot and counted my money again. It wasn't much. I 1 being poor, not having enough to 2 my small children a few simple toys. As I was 3 I noticed the Salvation Army (救世军) bell ringer at the4. I felt bad again because I didn't feel I could 5 anything to give him. I started walking towards the entrance 6 two cars entered empty parking spaces in front of me. The first was a7, new Cadillac which became the 8 of me the moment I saw it. “How 9 I thought, “would it be to have enough money to buy a car like that!” The second car10, was an ancient car more shabby than the one I was driving.
A man got out of the Cadillac and hurried into the store 11 past the bell ringer without a second 12. Out of the old car came a young mother with three small children following 13 behind her. Her clothes looked as 14 as her car, yet she slopped at the entrance and 15 a bill. In that second a(n)16 touched me, my envy and dislike 17 me, and all the love and joy filled me. I fished a bill out of my own purse18 it in the Salvation Army kettle, and wished the 19 a “Merry Christmas!”
Now I felt I was a poor man hut rich on the 20. After finding a few things for my kids, I drove home with my heart singing.
=R+2M中，已知R和M的摩尔质量之比为22∶9，当1.6 g X和Y完全反应后，生成4.4 g R。则在此反应中Y和M的质量之比为（ ）
