Decide which of the choices given below would correctly complete the passage if inserted in the corresponding blanks. Mark the correct choice for each blank.
Before we ask how radio, or electron tubes and transistors work in ___1___ actual radio set, let's first find out ___2___radio signals get from the broad-casting station to your___3___. We know that sound signals travel through the air in waves of high and low pressure. In a___4___similar way radio signals travel in waves of magnetism
Magnetism, you remember, is produced when electrons flow ___5___ a wire. Such magnetism, because it is electrically produced, is called ___6___.The heavier the electric current is, the ___7___the  electromagnetism.
In a transformer, the current alternates, or repeatedly changes direction in the___8___ winding. This causes waves of electromagnetism to move out from the winding, and these waves, cutting across the___9___ winding , cause___10___ (or current) to flow in the secondary winding .
Key:
1.a. an         b. the           c. a          d. /
2.a. what       b. how          c. that        d. which
3.receiver      b. sender         c. receive     d. send
4.a. what       b. same          c.somewhat   d. kind
5.a.through     b. across         c. by         d. /
6.a. electronics  b. electricity      c. magnetism  d.electromagnetism
7.a. strong      b. weak          c.stronger    d. weaker
8.a. primary     b. secondary      c. original    d. later
9. a. primary    b. secondary      c. original     d. later
10.a. electrons   b.electronics      c. electricity  d.electrical
Key: 1.a  2.b  3.a 4.c  5.a  6.d  7. c 8.a 9. b 10. a