Answer and Explanation:
1. The world's tallest man was eight feet, 11.1 inches when he died on July 15,1940. (Begin sentence with capital letter; the s in world is not plural but possessive; the name of the months are capitalized)
2. An Austrian man was both a dwarf and a giant during his adult life. (Begin sentence with capital letter; Capitalize gentilic ;these nouns use lowercase; his doesn't need apostrophe)
3. A woman from the Netherlands was the shortest female ever; she never weighed more than nine pounds in her life. (Capital letter to begin; also for gentilic; s for plural, not possessive)
4. One Russian peasant woman gave birth to sixty-nine children. (Capital letter to begin sentence and for gentilic, not for the noun; hyphen not needed between the two nouns, hyphen for tens and units; children is the plural)
5. Conjoined twins used to be called "Siamese" because of two very famous Thai brothers, Chang and Eng Bunker, who were joined at the chest. (Begin with capital letter; twins is the plural; capital letter for the gentilic; hyphen not needed after very)