To estimate the expansion rate of the universe is a notoriously difficult problem because there is a lack of a single yardstick that all distances can be measured by.
A. To estimate the expansion rate of the universe is a notoriously difficult problem because there is a lack of a single yardstick that all distances can be measured by.
B. Estimating the expansion rate of the universe is a notoriously difficult problem because there is no single yardstick by which all distances can be measured.
C. Because there is a lack of a single yardstick to measure all distances by, estimating the expansion rate of the universe is a notoriously difficult problem.
D. notoriously difficult problem is to estimate the expansion rate of the universe because a single yardstick is lacking by which all distances can be measured.
E. It is a notoriously difficult problem to estimate the expansion rate of the universe because by no single yardstick can all distances be measured.
A. To estimate the expansion rate of the universe is a notoriously difficult problem because there is a lack of a single yardstick that all distances can be measured by.
B. Estimating the expansion rate of the universe is a notoriously difficult problem because there is no single yardstick by which all distances can be measured.
C. Because there is a lack of a single yardstick to measure all distances by, estimating the expansion rate of the universe is a notoriously difficult problem.
D. notoriously difficult problem is to estimate the expansion rate of the universe because a single yardstick is lacking by which all distances can be measured.
E. It is a notoriously difficult problem to estimate the expansion rate of the universe because by no single yardstick can all distances be measured.












