Which type of epithelial tissue allows transportation of substances through a selective permeable surface in the lining of food vessels or lung alveoli?
In the following figure, rectangle represents Actors, circle represents Art critics, triangle represents Photographers and square represents Indians. Which set of letters represents Photographers who are either Actors or Art critics ?
The angle of elevation of the top of a pillar from the foot and the top of a building 20 m high, are 60° and 30° respectively. The height of the pillar is