___you understand this rule, you will have no further difficulty.
| A．Once | B．At once | C．Only | D．Only then |
Nineplusthree _________twelve.
| A．makes | B．make | C．ismaking | D．aremaking |
Twentymiles_________alongwaytocover.
| A．were | B．are | C．is | D．seemtobe |
Tenthousanddollars_________alargesumofmoney.
| A．are | B．is | C．were | D．seem |
Veryfew_________hisaddressinthetown.
| A．knows | B．know | C．areknowing | D．hasknown |
Notonlytheworkersbutalsothemachine____notthere.
| A．are | B．were | C．is | D．has |