【单选题】In 1977 the number of existing homes sold was approximately how many times the number of new homes sold?
【简答题】The number of protons in the nucleus of a tin atom is 50, while the number of neutrons in the nucleus is 68. The atomic number and the mass number of this isotope are( ) and ( ).
【简答题】S1:What was the number of person in liferafts?S2:The number of persons in liferafts was 25.Q:What is the topic?A. The number of liferafts launched. B. The number of persons in liferafts. C. The number...
【单选题】workers in the factory over two thousand.