砂浆应采用机械搅拌，搅拌时间自投料完算起，其中水泥粉煤灰砂浆和掺用外加剂的砂浆的搅拌时间不得少于（）min

A．水泥砂浆和水泥混合砂浆不得少于2min

B．水泥砂浆和水泥混合砂浆不得少于3min

C．水泥粉煤灰砂浆和掺用外加剂的砂浆不得少于2min

D．水泥粉煤灰砂浆和掺用外加剂的砂浆不得少于3min

A.100S

B.120S

C.150S

D.180S

A、1

B、1.5

C、2

D、3

A.{A:90}

B.{B:120}

C.{C:150}

D.{D:180}

A.60S

B.120S

C.150S

D.180S

A.1

B.2

C.3

D.5

A.20%以上

B.40%

C.30%-70%

D.40%-80%