A.光信號(hào)→數(shù)字信號(hào)→模擬電信號(hào) B.光信號(hào)→模擬電信號(hào)→數(shù)字信號(hào) C.模擬電信號(hào)→光信號(hào)→數(shù)字信號(hào) D.數(shù)字信號(hào)→光信號(hào)→模擬電信號(hào)
A、39條碼 B、EAN條碼 C、UPC條碼 D、EAN-13
A.字母長(zhǎng)度/m2 B.字母?jìng)€(gè)數(shù)/cm C.字母?jìng)€(gè)數(shù)/m3 D.字母長(zhǎng)度/cm