In the following passage some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.
Science is both a blessing and a _____. While it has given us many things which have made life better and _____, it has also given terrible instruments of _____. Science has discovered and invented many things to _____ pain and cure terrible diseases. These discoveries have enabled man to live a longer and _____ life.