China’s economy expanded 8.1 percent in the first quarter from a year earlier,___the slowest pace in almost three years.

A． marking

B． to mark

C． having marking

D． marked

SLZ综合录井仪检测的非烃组分是（）。

A、氢气和氮气

B、氮气和二氧化碳

C、氢气和二氧化碳

D、氮气和氦气