The Smiths _____ _  sending e-mails _____  letters, because it is faster. sending

A．prefer, to writing

B．prefer, to write

C．prefers, to write

D．prefers, to writing

0.4mm-0.5mm芯线线径的电缆Y型接续时需使用纸套管内径是（）。

A.3.0mm

B.3.5mm

C.4.5mm

D.5.5mm