C, F, H, K, P, Q, S, T, X, Ch, Sh, and Wh.

73. What Combination is both Aspirate and Subvocal?

Th.

74. What are Cognate letters?

Those which are produced by the same organs of speech in a similar position.

75. Give an example of a Cognate letter.

D is a cognate of T.

76. What are Quiescent letters?

Those that are silent.

77. How many uses have Silent letters?