After more than four decades of research and development, a new type of jet engine is beingtested that could eventually propel aircraft anywhere in the world within two hours or help boost cargoes into space at significantly lower costs than current methods permit.
(A) tested that could eventuallypropel aircraft anywhere in the world within two hoursor help
(B) tested thatcould eventually have thecapability of propelling aircraft anywhere in the world within two hoursor to help
(C) tested,
...
(A) tested that could eventuallypropel aircraft anywhere in the world within two hoursor help
(B) tested thatcould eventually have thecapability of propelling aircraft anywhere in the world within two hoursor to help
(C) tested,
...
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