Use appropriate sentence connectors in the blank spaces of the following passage. Scientists have always wondered (a)—- there is life anywhere out in the space besides us. (b)— they have joined together on a major project called the Communication with Extra-Terrestrial Intelligence (CET1) (c) ——-seeks to establish contact with any other living beings in the universe. (d) ——this they are beaming out radio signals into space in the hope of attracting attention of "other worlds". It was thought (e) —— there is life on Mars. (f)——-two Viking spacecrafts (g) ——landed on Mars in 1976 did not provide much evidence of life. The pictures sent by them showed Mars (h) ——having a red sky (i)—— a blue one like ours and a pinkish iron-rich soil. Us gravity is about half as strong as that of Earth (j) —— the atmosphere is also much thinner than our planet.