Since all squares are rectangles, and all rectangles have four sides, so all squares have four sides.
All numbers ending in 0 or 5 are divisible by 5. The number 35 ends with a 5, so it is divisible by 5.
Acute angles are less than 90 degrees and this angle is 40 degrees so this angle is acute.
The Earth is a planet, and all planets orbit a sun, therefore the Earth orbits a sun.
Cacti are plants and all plants perform photosynthesis; therefore, cacti perform photosynthesis.
William is a bachelor, all bachelors are single; hence William is single.