The price of(a) crude oil used to be a great (b) deal lower(c ) than now, wasn't it (d) ?
While nurturing parents can compensate for adversity, cold or inconsistent parents may...... it.
If the streets would have(a) been clearly(b) marked it would not have(c ) taken us so long to find his house (d) .
It is almost always desirable to increase the yield of a crop if ... increases are not also necessary in encrgy, labor, and other inputs of crop production.